Optical multiplexer/demultiplexer module and associated methods

ABSTRACT

A TORminator module is disposed with a switch linecard of a rack. The TORminator module receives downlink electrical data signals from a rack switch. The TORminator module translates the downlink electrical data signals into downlink optical data signals. The TORminator module transmits multiple subsets of the downlink optical data signals through optical fibers to respective SmartDistributor modules disposed in respective racks. Each SmartDistributor module receives multiple downlink optical data signals through a single optical fiber from the TORminator module. The SmartDistributor module demultiplexes the multiple downlink optical data signals and distributes them to respective servers. The SmartDistributor module receives multiple uplink optical data signals from multiple servers and multiplexes them onto a single optical fiber for transmission to the TORminator module. The TORminator module coverts the multiple uplink optical data signals to multiple uplink electrical data signals, and transmits the multiple uplink electrical data signals to the rack switch.

CLAIM OF PRIORITY

This application is a continuation application under 35 U.S.C. 120 ofprior U.S. application Ser. No. 16/510,829, filed Jul. 12, 2019, whichclaims priority under 35 U.S.C. 119(e) to each of: 1) U.S. ProvisionalPatent Application No. 62/697,344, filed Jul. 12, 2018; 2) U.S.Provisional Patent Application No. 62/698,856, filed Jul. 16, 2018; and3) U.S. Provisional Patent Application No. 62/722,443, filed Aug. 24,2018. The disclosure of each above-identified application isincorporated herein by reference in its entirety for all purposes.

BACKGROUND 1. Field of the Invention

The present invention relates to optical data communication.

2. Description of the Related Art

Optical data communication systems operate by modulating laser light toencode digital data patterns. The modulated laser light is transmittedthrough an optical data network from a sending node to a receiving node.The modulated laser light having arrived at the receiving node isde-modulated to obtain the original digital data patterns. Therefore,implementation and operation of optical data communication systems isdependent upon having reliable and efficient mechanisms for transmittinglaser light and detecting laser light at different nodes within theoptical data network. In this regard, it can be necessary to convertdata streams from an electrical domain to an optical domain, andvice-versa, and transmit data streams between various physicallydistributed computing systems. It is within this context that thepresent invention arises.

SUMMARY

In an example embodiment, a data communication system is disclosed. Thedata communication system includes a rack switch, a TORminator module,downlink optical fiber, an uplink optical fiber, and a SmartDistribuTORmodule. The TORminator module is electrically connected to the rackswitch. The TORminator module is configured to convert a number (N) ofdownlink data communication electrical signals received from the rackswitch into corresponding N downlink data communication optical signals.The value of N is greater than one. Each of the N downlink datacommunication optical signals has a different optical wavelength. TheTORminator module is configured to simultaneously direct the N downlinkdata communication optical signals to a first downlink optical port. TheTORminator module is configured to generate N different wavelengths ofcontinuous wave laser light and simultaneously direct the N differentwavelengths of continuous wave laser light to the first downlink opticalport. The TORminator module includes a first uplink optical port. TheTORminator module is configured to convert N uplink data communicationoptical signals received through the first uplink optical port into Nuplink data communication electrical signals. The TORminator module isconfigured to transmit the N uplink data communication electricalsignals to the rack switch. The downlink optical fiber has a first endoptically coupled to the first downlink optical port of the TORminatormodule. The uplink optical fiber has a first end optically coupled tothe first uplink optical port of the TORminator module. TheSmartDistribuTOR module has a second downlink optical port, a seconduplink optical port, N server downlink optical ports, and N serveruplink optical ports. The downlink optical fiber has a second endoptically coupled to the second downlink optical port. The uplinkoptical fiber has a second end optically coupled to the second uplinkoptical port. The SmartDistribuTOR module is configured to respectivelydirect the N downlink data communication optical signals and the Ndifferent wavelengths of continuous wave laser light received throughthe second downlink optical port to the N server downlink optical ports.The SmartDistribuTOR module is configured to simultaneously direct Nuplink data communication optical signals received through the N serveruplink optical ports to the second uplink optical port.

In an example embodiment, a method is disclosed for controlling datacommunication. The method includes receiving a number (N) of downlinkdata communication electrical signals from a rack switch at a TORminatormodule. The value of N is greater than one. The method also includesoperating the TORminator module to convert the N downlink datacommunication electrical signals into corresponding N downlink datacommunication optical signals. Each of the N downlink data communicationoptical signals has a different optical wavelength. The method alsoincludes operating the TORminator module to simultaneously direct the Ndownlink data communication optical signals to a first downlink opticalport of the TORminator module. The method also includes operating theTORminator module to generate N different wavelengths of continuous wavelaser light. The method also includes operating the TORminator module tosimultaneously direct the N different wavelengths of continuous wavelaser light to the first downlink optical port of the TORminator module.The method also includes operating the TORminator module to receive Nuplink data communication optical signals through a first uplink opticalport of the TORminator module. The method also includes operating theTORminator module to convert the N uplink data communication opticalsignals into N uplink data communication electrical signals. The methodalso includes operating the TORminator module to transmit the N uplinkdata communication electrical signals to the rack switch.

In an example embodiment, an optical multiplexer/demultiplexer module isdisclosed. The optical multiplexer/demultiplexer module includes adownlink optical port, an uplink optical port, a number (N) of serverdownlink optical ports, N server uplink optical ports, an opticaldemultiplexer, and an optical multiplexer. The optical demultiplexer isconfigured to separate N downlink data communication optical signalsreceived through the downlink optical port based on optical wavelength.The optical demultiplexer is configured to respectively direct the Ndownlink data communication optical signals to the N server downlinkoptical ports. The optical demultiplexer is configured to separate Ndifferent wavelengths of continuous wave laser light received throughthe downlink optical port based on optical wavelength. The opticaldemultiplexer is configured to respectively direct the N differentwavelengths of continuous wave laser light to the N server downlinkoptical ports. The optical multiplexer is configured to aggregate Nuplink data communication optical signals received through the N serveruplink optical ports onto a single optical waveguide optically coupledto the uplink optical port.

In an example embodiment, a method is disclosed for operating an opticalmultiplexer/demultiplexer module. The method includes receiving a number(N) of downlink data communication optical signals through a downlinkoptical port. The method also includes separating the N downlink datacommunication optical signals into N separate optical channels. Themethod also includes receiving N different wavelengths of continuouswave laser light through the downlink optical port. The method alsoincludes separating the N different wavelengths of continuous wave laserlight into the N separate optical channels. The method also includesrespectively directing the N separate optical channels to N serverdownlink optical ports. The method also includes respectively receivingN uplink data communication optical signals through the N server uplinkoptical ports. The method also includes aggregating the N uplink datacommunication optical signals onto a single optical waveguide opticallycoupled to an uplink optical port.

In an example embodiment, an electro-optical interface module indisclosed. The electro-optical interface module includes an opticalfiber interface configured to optically couple to a first optical fiberand a second optical fiber. The electro-optical interface module alsoincludes an electronic-photonic chip that includes a first opticalcoupler and a second optical coupler. The first optical coupler isconfigured and connected to receive light transmitted through theoptical fiber interface from the first optical fiber. The second opticalcoupler is configured and connected to direct light through the opticalfiber interface to the second optical fiber. The electronic-photonicchip includes a downlink polarization control device configured to splitlight received through the first optical coupler into a firstpolarization of light and a second polarization of light. Theelectronic-photonic chip includes a downlink data receiver deviceconfigured and connected to receive light from the downlink polarizationcontrol device. The downlink data receiver device is configured andconnected to filter downlink modulated light from the light receivedfrom the downlink polarization control device and convert the downlinkmodulated light into a downlink electrical data signal. The downlinkdata receiver device is configured and connected to direct unmodulatedcontinuous wave light received from the downlink polarization controldevice to an optical output of the downlink data receiver device. Theelectronic-photonic chip includes an uplink data modulator deviceconfigured and connected to receive the unmodulated continuous wavelight from the optical output of the downlink polarization controldevice. The uplink data modulator device is configured and connected toimprint an uplink electrical data signal on the unmodulated continuouswave light to generate uplink modulated light. The uplink data modulatordevice is configured and connected to direct the uplink modulated lightto the second optical coupler. The electronic-photonic chip alsoincludes an electrical input/output block configured and connected toreceive the downlink electrical data signal from the downlink datareceiver device and direct the downlink electrical data signal tocircuitry external to the electronic-photonic chip. The electricalinput/output block is configured and connected to receive the uplinkelectrical data signal from circuitry external to theelectronic-photonic chip and direct the uplink electrical data signal tothe uplink data modulator device.

In an example embodiment, a method is disclosed for operating anelectro-optical interface of a server. The method includes receivingdownlink light through a first optical coupler, where the downlink lightincludes downlink modulated light of a first wavelength and unmodulatedcontinuous wave light of a second wavelength. The method also includesfiltering the downlink modulated light from the downlink light. Themethod also includes converting the downlink modulated light into adownlink electrical data signal. The method also includes transmittingthe downlink electrical data signal to processing circuitry. The methodalso includes imprinting an uplink electrical data signal on theunmodulated continuous wave light to generate uplink modulated light.The method also includes transmitting the uplink modulated light throughthe a second optical coupler.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of a TORminator system, in accordance with someembodiments.

FIG. 2A shows an example schematic of a TORminator module, in accordancewith some embodiments.

FIG. 2B shows an example architectural diagram of a laser chip, inaccordance with some embodiments of the present invention.

FIG. 2C shows an example architectural diagram of a TeraPHY chip, inaccordance with some embodiments.

FIG. 2D shows an example schematic diagram of a TeraPHY chip, inaccordance with some embodiments.

FIG. 2E shows an example schematic diagram of chip-to-chip optical datacommunication, in accordance with some embodiments.

FIG. 2F shows an example transceiver macro implemented within theTeraPHY chip, in accordance with some embodiments.

FIG. 3 shows a schematic of one SmartDistribuTOR module with an exampledownlink fiber wavelength plan for the downlink optical fiber and anexample uplink fiber wavelength plan for the uplink optical fiber, inaccordance with some embodiments.

FIG. 4 shows a schematic of the tunable optical DEMUX block within theSmartDistribuTOR module, in accordance with some embodiments.

FIG. 5 shows a schematic of the tunable optical MUX block within theSmartDistribuTOR module, in accordance with some embodiments.

FIG. 6 shows a schematic of a server-side electro-optical module(“Reverb module”) within a server, in accordance with some embodiments.

FIG. 7 shows a schematic of the Reverb chip, in accordance with someembodiments.

FIG. 8 shows an example uplink and downlink wavelength plan per downlinkoptical fiber and uplink optical fiber, in accordance with someembodiments.

FIG. 9 shows the TORminator system implemented across multiple rackswithin a datacenter, in accordance with some embodiments.

FIG. 10 shows a flowchart of a method for controlling datacommunication, in accordance with some embodiments.

FIG. 11 shows a flowchart of a method for operating an opticalmultiplexer/demultiplexer module, in accordance with some embodiments.

FIG. 12 shows a flowchart of a method for operating an electro-opticalinterface of a server, in accordance with some embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide an understanding of the present invention. It will beapparent, however, to one skilled in the art that the present inventionmay be practiced without some or all of these specific details. In otherinstances, well known process operations have not been described indetail in order not to unnecessarily obscure the present invention.

In current data-centers, servers are organized in racks. Each rackincludes a Top-of-Rack (TOR) switch, which connects the servers in therack to the rest of the data-center network (typically called the coreor the spine). Since the throughput of the switches increases fasterthan the throughput needs of each individual server in the rack, thereexists an opportunity for a single switch to feed more than one rack,thereby eliminating a stage in the network hierarchy and providingsignificant latency and cost savings. This network architecture is knownas End-of-Row (EOR) or Middle-of-Row (MOR), depending on the location ofthe switch within a row of racks. Specifically, EOR architecture has theswitch located in the rack at the end of the row, and MOR architecturehas the switch located in the rack at the middle of the row. In currentdata-centers, TOR architecture (in which a switch is located at the topof each rack) is preferred since rack-to-spine links are optical, whilethe dense server-to-TOR switch links are electrical, which minimizes thecabling costs.

Systems and methods are disclosed herein that utilize highly integratedelectronic-photonic transceiver technology to provide a new EOR/MORarchitecture in which photonic interconnects connect the servers invarious racks to the EOR/MOR switch, enabling row connectivitycapability that overcomes the length limitations of traditional coppercabling. This new EOR/MOR architecture is referred to as a “TORminatorsystem” 100.

FIG. 1 shows a schematic of the TORminator system 100, in accordancewith some embodiments. FIG. 1 shows the connectivity within theTORminator system 100 between one EOR/MOR switch linecard 101 and anumber (M) of servers. In the example of FIG. 1 , M equals 128, suchthat the one EOR/MOR switch linecard 101 and the TORminator system 100services 128 servers. In some embodiments, the M servers are distributedacross multiple racks. In some embodiments, each rack includes a number(N) of servers. In the example of FIG. 1 , N equals 8, with each rackincluding 8 servers.

A rack switch 103 in the linecard 101 is connected electrically to aTORminator module 107 on the linecard 101 through an electrical bus 105.In some embodiments, the electrical bus 105 is a 128 data communicationlane, Pulse-Amplitude Modulation 4-Level (PAM4), Very Short Reach (VSR)bus operating at 100 gigabits per second per lane (Gbps/lane). In someembodiments, each data communication lane of the electrical bus 105 is afull-duplex differential signaling lane that includes one pair ofconductors for transmitting data and one pair of conductors forreceiving data. However, it should be understood that in otherembodiments, alternative data communication lane configurations can beimplemented. It should also be understood that in other embodiments, theelectrical bus 105 can be configured to have more or less than 128 datacommunication lanes and can operate at either higher data rates or lowerdata rates than 100 Gbps/lane. In some embodiments, each datacommunication lane in the electrical bus 105 is designated to service adifferent server in the datacenter. Therefore, in some embodiments, theTORminator system 100 is configured to connect with 128 servers, and theelectrical bus 105 is configured to include 128 data communicationlanes.

The TORminator module 107 is configured and connected to convert thedata from the electrical domain of the rack switch 103 to the opticaldomain that exists between the TORminator module 107 and the servers.The TORminator module 107 is configured to send data in the opticaldomain to a number (K) of SmartDistribuTOR modules 111-1 through 111-K.In the example of FIG. 1 , K equals 16, such that the TORminator module107 is configured to send data in the optical domain to 16SmartDistribuTOR modules 111-1 through 111-16. It should be understood,however, that in other embodiments the number K of SmartDistribuTORmodules 111-1 through 111-K that are connected to a given TORminatormodule 107 can be either less than or greater than 16. The TORminatormodule 107 includes K duplex optical ports 109-1 through 109-K. Eachoptical port 109-1 through 109-K provides for optical coupling to arespective downlink optical fiber d1 through dK, and for opticalcoupling to a respective uplink optical fiber u1 through uK. In theexample of FIG. 1 , because K is 16, there are 16 optical ports 109-1through 109-16 that respectively provide for optical coupling todownlink optical fibers d1 through d16, and that respectively providefor optical coupling to uplink optical fibers u1 through u16.

Each pair of downlink optical fibers d1 through dK and uplink opticalfibers u1 through uK is connected to a respective one of theSmartDistribuTOR modules 111-1 through 111-K. For example, in FIG. 1 ,the pair of downlink optical fiber d1 and uplink optical fiber u1 isconnected to the SmartDistribuTOR modules 111-1. Similarly, the pair ofdownlink optical fiber d16 and uplink optical fiber u16 is connected tothe SmartDistribuTOR modules 111-16. Each of the SmartDistribuTORmodules 111-1 through 111-K has a duplex optical port 113 to which thecorresponding downlink optical fiber d1 through dK and correspondinguplink optical fiber u1 through uK are connected.

In some embodiments, each of the SmartDistribuTOR modules 111-1 through111-K is installed in a corresponding rack, e.g., at the top of acorresponding rack. Generally speaking, the SmartDistribuTOR module111-1 through 111-K splits multiple optical channels from thecorresponding downlink optical fiber d1 through dK, and respectivelydirects the multiple optical channels to multiple servers in the rack inwhich the SmartDistribuTOR module is located. Each optical channelincludes at least one modulated laser light wavelength and at least onecontinuous wave (unmodulated) laser light wavelength.

FIG. 1 shows a schematic of the SmartDistribuTOR module 111-1 through111-K with an example uplink and downlink wavelength plan per uplink anddownlink optical fiber, in accordance with some embodiments. In someembodiments, dense wavelength division multiplexing (DWDM) can be usedto pack a large number of optical channels and increase the number ofservers reachable via a single uplink and downlink optical fiber pair.Each SmartDistribuTOR module 111-1 through 111-K includes a downlinkoptical waveguide 115 optically coupled through the optical port 113 tothe corresponding downlink optical fiber d1 through dK. The downlinkoptical waveguide 115 is optically connected to an optical demultiplexer119 that is configured to separate N downlink data communication opticalsignals received through the downlink optical waveguide 115 based onoptical wavelength. The optical demultiplexer 119 is also configured torespectively direct the N downlink data communication optical signals toN server downlink optical ports S1 d through SNd.

For example, FIG. 1 shows eight optical channels Ch1 through Ch8transmitted through the downlink optical waveguide 115, with onemodulated wavelength per optical channel Ch1 through Ch8, and with oneunmodulated continuous wave wavelength per optical channel Ch1 throughCh8. Specifically, optical channel Ch1 includes one unmodulatedcontinuous wave wavelength designated as signal 1, and one modulatedwavelength designated as signal 2. Optical channel Ch2 includes oneunmodulated continuous wave wavelength designated as signal 3, and onemodulated wavelength designated as signal 4. Optical channel Ch3includes one unmodulated continuous wave wavelength designated as signal5, and one modulated wavelength designated as signal 6. Optical channelCh4 includes one unmodulated continuous wave wavelength designated assignal 7, and one modulated wavelength designated as signal 8. Opticalchannel Ch5 includes one unmodulated continuous wave wavelengthdesignated as signal 9, and one modulated wavelength designated assignal 10. Optical channel Ch6 includes one unmodulated continuous wavewavelength designated as signal 11, and one modulated wavelengthdesignated as signal 12. Optical channel Ch7 includes one unmodulatedcontinuous wave wavelength designated as signal 13, and one modulatedwavelength designated as signal 14. Optical channel Ch8 includes oneunmodulated continuous wave wavelength designated as signal 15, and onemodulated wavelength designated as signal 16. In some embodiments, eachmodulated wavelength can carry 100 gigabits per second (Gbps) of data,by way of example. In some embodiments, each modulated wavelength cancarry either more than or less than 100 Gbps of data.

In the example of FIG. 1 , the optical demultiplexer 119 is configuredto separate eight downlink data communication optical signals (signals2, 4, 6, 8, 10, 12, 14, and 16) received through the downlink opticalwaveguide 115 based on optical wavelength. The optical demultiplexer 119is also configured to respectively direct the eight downlink datacommunication optical signals (signals 2, 4, 6, 8, 10, 12, 14, and 16)through eight respective optical waveguides 123 to eight server downlinkoptical ports S1 d through S8 d. The optical demultiplexer 119 is alsoconfigured to separate eight unmodulated continuous wave optical signals(signals 1, 3, 5, 7, 9, 11, 13, and 15) received through the downlinkoptical waveguide 115 based on optical wavelength. The opticaldemultiplexer 119 is also configured to respectively direct the eightunmodulated continuous wave optical signals (signals 1, 3, 5, 7, 9, 11,13, and 15) through the eight respective optical waveguides 123 to theeight server downlink optical ports S1 d through S8 d. Therefore, eachserver downlink optical port S1 d through S8 d transmits one downlinkdata communication optical signal and one unmodulated continuous waveoptical signal to a corresponding server.

For example, both the unmodulated continuous wave optical signal 1 andthe downlink data communication optical signal 2 that constitute channelCh1 are transmitted through one of the optical waveguides 123 to theserver downlink optical port S1 d and through an optical fiber d11 tothe server 1. Both the unmodulated continuous wave optical signal 3 andthe downlink data communication optical signal 4 that constitute channelCh2 are transmitted through one of the optical waveguides 123 to theserver downlink optical port S2 d and through an optical fiber d12 tothe server 2. Both the unmodulated continuous wave optical signal 5 andthe downlink data communication optical signal 6 that constitute channelCh3 are transmitted through one of the optical waveguides 123 to theserver downlink optical port S3 d and through an optical fiber d13 tothe server 3. Both the unmodulated continuous wave optical signal 7 andthe downlink data communication optical signal 8 that constitute channelCh4 are transmitted through one of the optical waveguides 123 to theserver downlink optical port S4 d and through an optical fiber d14 tothe server 4. Both the unmodulated continuous wave optical signal 9 andthe downlink data communication optical signal 10 that constitutechannel Ch5 are transmitted through one of the optical waveguides 123 tothe server downlink optical port S5 d and through an optical fiber d15to the server 5. Both the unmodulated continuous wave optical signal 11and the downlink data communication optical signal 12 that constitutechannel Ch6 are transmitted through one of the optical waveguides 123 tothe server downlink optical port S6 d and through an optical fiber d16to the server 6. Both the unmodulated continuous wave optical signal 13and the downlink data communication optical signal 14 that constitutechannel Ch7 are transmitted through one of the optical waveguides 123 tothe server downlink optical port S7 d and through an optical fiber d17to the server 7. Both the unmodulated continuous wave optical signal 15and the downlink data communication optical signal 16 that constitutechannel Ch8 are transmitted through one of the optical waveguides 123 tothe server downlink optical port S8 d and through an optical fiber d18to the server 8.

Each SmartDistribuTOR module 111-1 through 111-K also includes an uplinkoptical waveguide 117 optically coupled through the optical port 113 tothe corresponding uplink optical fiber u1 through uK. The uplink opticalwaveguide 117 is connected to the optical output of an opticalmultiplexer 121. The optical multiplexer 121 is configured to aggregateN uplink data communication optical signals received through the Nserver uplink optical ports S1 u through SNu onto the single opticalwaveguide 117 optically coupled to the optical port 113. The example ofFIG. 1 shows eight optical channels Ch1 through Ch8 on the uplinkoptical waveguide 117, with one modulated wavelength per optical channelCh1 through Ch8.

In the example of FIG. 1 , the SmartDistribuTOR module 111-1 includeseight server uplink optical ports S1 u through S8 u. The server uplinkoptical port S1 u is connected to an uplink optical fiber u11 throughwhich an uplink data communication optical signal 1 is transmitted. Theserver uplink optical port S1 u is optically connected through acorresponding one of optical waveguides 125 to the optical multiplexer121. The server uplink optical port S2 u is connected to an uplinkoptical fiber u12 through which an uplink data communication opticalsignal 3 is transmitted. The server uplink optical port S2 u isoptically connected through a corresponding one of optical waveguides125 to the optical multiplexer 121. The server uplink optical port S3 uis connected to an uplink optical fiber u13 through which an uplink datacommunication optical signal 5 is transmitted. The server uplink opticalport S3 u is optically connected through a corresponding one of opticalwaveguides 125 to the optical multiplexer 121. The server uplink opticalport S4 u is connected to an uplink optical fiber u14 through which anuplink data communication optical signal 7 is transmitted. The serveruplink optical port S4 u is optically connected through a correspondingone of optical waveguides 125 to the optical multiplexer 121. The serveruplink optical port S5 u is connected to an uplink optical fiber u15through which an uplink data communication optical signal 9 istransmitted. The server uplink optical port S5 u is optically connectedthrough a corresponding one of optical waveguides 125 to the opticalmultiplexer 121. The server uplink optical port S6 u is connected to anuplink optical fiber u16 through which an uplink data communicationoptical signal 11 is transmitted. The server uplink optical port S6 u isoptically connected through a corresponding one of optical waveguides125 to the optical multiplexer 121. The server uplink optical port S7 uis connected to an uplink optical fiber u17 through which an uplink datacommunication optical signal 13 is transmitted. The server uplinkoptical port S7 u is optically connected through a corresponding one ofoptical waveguides 125 to the optical multiplexer 121. The server uplinkoptical port S8 u is connected to an uplink optical fiber u18 throughwhich an uplink data communication optical signal 15 is transmitted. Theserver uplink optical port S8 u is optically connected through acorresponding one of optical waveguides 125 to the optical multiplexer121.

The uplink data communication optical signal 1 constitutes uplinkchannel Ch1. The uplink data communication optical signal 3 constitutesuplink channel Ch2. The uplink data communication optical signal 5constitutes uplink channel Ch3. The uplink data communication opticalsignal 7 constitutes uplink channel Ch4. The uplink data communicationoptical signal 9 constitutes uplink channel Ch5. The uplink datacommunication optical signal 11 constitutes uplink channel Ch6. Theuplink data communication optical signal 13 constitutes uplink channelCh7. The uplink data communication optical signal 15 constitutes uplinkchannel Ch8. In some embodiments, each modulated wavelengthcorresponding to uplink data communication optical signals 1, 3, 5, 7,9, 11, 13, and 15 can carry 100 Gbps of data, by way of example. In someembodiments, each modulated wavelength corresponding to uplink datacommunication optical signals 1, 3, 5, 7, 9, 11, 13, and 15 can carryeither more than or less than 100 Gbps of data.

As shown in FIG. 1 , an electro-optical module Rvb-1 through Rvb-M(“Reverb”) is provided at each of servers 1 through M, respectively.Generally speaking, each electro-optical module Rvb-1 through Rvb-Mreceives at least one optical channel and converts the modulated opticalwavelength on the received optical channel to an electrical data-streamwhich is then forwarded to a network interface of the correspondingserver as downlink traffic. Also, the electro-optical module Rvb-1through Rvb-M at each of servers 1 through M, respectively, modulatesthe continuous wave laser light wavelength with data provided by thenetwork interface of the corresponding server for uplink connection tothe rack switch 103 in the EOR/MOR switch linecard 101.

On the uplink connection path, modulated optical wavelengths fromseveral of the electro-optical modules Rvb-1 through Rvb-M of severalcorresponding servers 1 through M are multiplexed together by theoptical multiplexer 121 within the SmartDistribuTOR module 111-1 through111-K onto corresponding optical fibers u1 through uK connecting theSmartDistribuTOR module 111-1 through 111-K with the TORminator module107 on the EOR/MOR switch linecard 101. For example, FIG. 1 shows thatmodulated optical wavelengths from electro-optical modules Rvb-1 throughRvb-8 of corresponding servers 1 through 8 are multiplexed together bythe optical multiplexer 121 within the SmartDistribuTOR module 111-1onto the uplink optical waveguide 117 for transmission over the opticalfiber u1 that connects the SmartDistribuTOR module 111-1 with theTORminator module 107 on the EOR/MOR switch linecard 101. Similarly,FIG. 1 shows that modulated optical wavelengths from electro-opticalmodules Rvb-121 through Rvb-128 of corresponding servers 121 through 128are multiplexed together by the optical multiplexer 121 within theSmartDistribuTOR module 111-16 onto the uplink optical waveguide 117 fortransmission over the optical fiber u16 that connects theSmartDistribuTOR module 111-16 with the TORminator module 107 on theEOR/MOR switch linecard 101. The TORminator module 107 converts multiplemodulated optical wavelengths from multiple optical fibers into amultiple corresponding electrical data streams that are forwarded to therack switch 103 on the linecard 101 as uplink data traffic.

FIG. 2A shows an example schematic of the TORminator module 107, inaccordance with some embodiments. The TORminator module 107 includes amulti-port, multi-wavelength-per-port laser supply chip 205 (e.g.,SuperNova laser chip by Ayar Labs, Inc.) that provides multiplewavelengths of laser light to a TeraPHY chip 203, as indicated byoptical connection 213. The TeraPHY chip 203 within the TORminatormodule 107 receives the electrical downlink data stream from the rackswitch 103, via an optional serializer/deserializer (SerDes) chip 201,as indicated by electrical connection 211. The TeraPHY chip 203modulates the wavelengths of laser light provided by the laser supplychip 205 with the electrical downlink data stream. In some embodiments,the optical signals from the TeraPHY chip 203 go directly to theSmartDistribuTOR modules 111-1 through 111-K through the optical ports109-1 through 109-K and corresponding optical fibers d1 through dK. Insome embodiments, the optical signals from the TeraPHY chip 203 aretransmitted through optical connection 217 to a downlink semiconductoroptical amplifier (SOA) array chip 207 (e.g., Arc SOA chip) thatoperates to amplify the optical signals before the optical signals aretransmitted from the TORminator module 107 to the SmartDistribuTORmodules 111-1 through 111-K. FIG. 2A shows a collection of opticalwaveguides 221 configured to convey the optical signals form the SOAchip 207 to the respective optical ports 109-1 through 109-K.

In some embodiments, the optical uplink signals received by theTORminator module 107 from the SmartDistribuTOR modules 111-1 through111-K are coupled directly to the TeraPHY chip 203. The TeraPHY chip 203functions to convert the received optical uplink signals to electricaldata streams and forward the electrical data streams to the rack switch103. In some embodiments, the electrical data streams are processed bythe SerDes chip 201 in route to the rack switch 103. In someembodiments, the optical uplink signals received by the TORminatormodule 107 from the SmartDistribuTOR modules 111-1 through 111-K arefirst coupled into an SOA array chip 209 (e.g., Arc SOA chip) foramplification. FIG. 2A shows a collection of optical waveguides 219configured to convey the optical signals form the respective opticalports 109-1 through 109-K to the SOA chip 209. Then, the amplifiedoptical uplink signals are coupled/transmitted from the SOA array chip209 through optical connection 215 into the TeraPHY chip 203.

In some embodiments, the TeraPHY chip 203 includes silicon-photoniccomponents driven by the SerDes chip 201. In some embodiments, theTeraPHY chip 203 includes silicon-photonic components and electronictransceiver circuitry monolithically integrated on the same die. In someembodiments, the laser chip 205 is implemented in an Indium Phosphide(InP) process. In some embodiments, the SOA array chip 207 isimplemented in an InP process capable of handling both polarizations oflight. And, in some embodiments, the SOA array chip 209 is implementedin an InP process capable of handling both polarizations of light.

In some embodiments, the TORminator module 107 is an edge-pluggablemodule having the laser chip 205, the SerDes chip 201, the TeraPHY chip203, and the SOA array chips 207, 209 packaged on a printed circuitboard (PCB) of the TORminator module 107. In these embodiments, theTORminator module 107 can be connected to the edge-style pluggableconnector mounted on the EOR/MOR switch linecard 101. In someembodiments, the TORminator module 107 is connected to the EOR/MORswitch linecard 101 using a mezzanine connector. In some embodiments,the TeraPHY chip 203, the laser chip 205, and the SOA array chips 207,209 are socketed to the EOR/MOR switch linecard 101. In someembodiments, the TeraPHY chip 203 is co-packaged with the rack switch103, while the laser chip 205 and the SOA array chips 207, 209 aremounted separately to the EOR/MOR switch linecard 101.

In some embodiments, the multiple wavelengths (e.g., 16 wavelengths) oflaser light provided by the laser chip 205 are coupled to one or moreoptical transceiver macros on the TeraPHY chip 203. Each opticaltransceiver macro on the TeraPHY chip 203 includes a transmit macro anda receive macro. Each of the transmit and receive macros includes slices(one slice per wavelength). The transmit macro includes a common opticalwaveguide and a number of ring modulators (one per slice) coupled intothe common optical waveguide, where each ring modulator is centered tomodulate one of the incoming wavelengths from the laser chip 205. Insome embodiments, the ring modulators in the transmit macro areconfigured according to the channelized wavelength plan as shown in theSmartDistribuTOR modules 111-1 through 111-K of FIG. 1 , such that someof the wavelengths are modulated for downlink traffic and some of thewavelengths are left unmodulated to be forwarded to the servers 1through N connected to the corresponding SmartDistribuTOR module toprovide for modulation of uplink data communication traffic. In someembodiments, the ring modulators in each slice are driven by theelectrical circuits in that slice on the same TeraPHY chip 203. Or, insome embodiments, the ring modulators in each slice are driven by theelectrical circuits on a separate die. In the receiver macro, aring-resonator filter in each slice drops a corresponding wavelengthfrom the common optical waveguide. This corresponding wavelength is thenconverted into an electrical signal by a photodetector embedded in thatslice. In some embodiments, the photodetector and the ring filter arecombined into a single structure. In some embodiments, the electricalsignal from the photodetector is further amplified by the receivercircuits on the same TeraPHY chip 203 and forwarded to the rack switch103. In some embodiments, the TeraPHY chip 203 includes only opticalcomponents, and the associated electrical circuit components are locatedon a separate chip. In some embodiments, the electrical link between therack switch 103 and the electro-optical components in the TeraPHY chip203 is retimed. However, in some embodiments, the electrical linkbetween the rack switch 103 and the electro-optical components in theTeraPHY chip 203 is not retimed.

The laser chip 205 is designed and configured to supply laser lighthaving one or more wavelengths. It should be understood that the term“wavelength” as used herein refers to the wavelength of electromagneticradiation. And, the term “light” as used herein refers toelectromagnetic radiation within a portion of the electromagneticspectrum that is usable by optical data communication systems. In someembodiments, the portion of the electromagnetic spectrum includes lighthaving wavelengths within a range extending from about 1100 nanometersto about 1565 nanometers (covering from the O-Band to the C-Band,inclusively, of the electromagnetic spectrum). However, it should beunderstood that the portion of the electromagnetic spectrum as referredto herein can include light having wavelengths either less than 1100nanometers or greater than 1565 nanometers, so long as the light isusable by an optical data communication system for encoding,transmission, and decoding of digital data throughmodulation/de-modulation of the light. In some embodiments, the lightused in optical data communication systems has wavelengths in thenear-infrared portion of the electromagnetic spectrum. Also, the term“laser beam” as used herein refers to a beam of light generated by alaser device. It should be understood that a laser beam may be confinedto propagate in an optical waveguide, such as (but not limited to) anoptical fiber or an optical waveguide within a planar lightwave circuit(PLC). In some embodiments, the laser beam is polarized. And, in someembodiments, the light of a given laser beam has a single wavelength,where the single wavelength can refer to either essentially onewavelength or can refer to a narrow band of wavelengths that can beidentified and processed by an optical data communication system as ifit were a single wavelength.

FIG. 2B shows an example architectural diagram of the laser chip 205, inaccordance with some embodiments of the present invention. The laserchip 205 includes a laser source 231 and an optical marshalling module233. The laser source 231 is configured to generate and output aplurality of laser beams, i.e., (X) laser beams. The plurality of laserbeams have different wavelengths (λ₁-λ_(X)) relative to each other,where the different wavelengths (λ₁-λ_(X)) are distinguishable to anoptical data communication system. In some embodiments, the laser source231 includes a plurality of lasers 235-1 to 235-X for respectivelygenerating the plurality (X) of laser beams, where each laser 235-1 to235-X generates and outputs a laser beam at a respective one of thedifferent wavelengths (λ₁-λ_(X)). Each laser beam generated by theplurality of lasers 235-1 to 235-X is provided to a respective opticaloutput port 237-1 to 237-X of the laser source 231 for transmission fromthe laser source 231. In some embodiments, each of the plurality oflasers 235-1 to 235-X is a distributed feedback laser configured togenerate laser light at a particular one of the different wavelengths(λ₁-λ_(X)). In some embodiments, the laser source 231 can be defined asa separate component, such as a separate chip. However, in otherembodiments, the laser source 231 can be integrated within a planarlightwave circuit (PLC) on a chip that includes other components inaddition to the laser source 231.

In the example embodiment of FIG. 2B, the laser source 231 is defined asa separate component attached to a substrate 230, such as an electronicpackaging substrate. In various embodiments, the substrate 230 can be anorganic substrate or a ceramic substrate, or essentially any other typeof substrate upon which electronic devices and/or optical-electronicdevices and/or optical waveguides and/or optical fiber(s)/fiberribbon(s) can be mounted. For example, in some embodiments, thesubstrate 230 can be an Indium-Phosphide (III-V) substrate. Or, inanother example, the substrate 230 can be an Al₂O₃ substrate. It shouldbe understood that in various embodiments the laser source 231 can beattached/mounted to the substrate 230 using essentially any knownelectronic packaging process, such as flip-chip bonding, which canoptionally include disposition of a ball grid array (BGA), bumps,solder, under-fill, and/or other component(s), between the laser source231 and the substrate 230, and include bonding techniques such as massreflow, thermal-compression bonding (TCB), or essentially any othersuitable bonding technique.

The optical marshalling module 233 is configured to receive theplurality of laser beams of the different wavelengths (λ₁-λ_(X)) fromthe laser source 231 at a corresponding plurality of optical input ports239-1 to 239-X of the optical marshalling module 233. The opticalmarshalling module 233 is also configured to distribute a portion ofeach of the plurality of laser beams to each of a plurality of opticaloutput ports 241-1 to 241-Y of the optical marshalling module 233, where(Y) is the number of optical output ports of the optical marshallingmodule 233. The optical marshalling module 233 operates to distributethe plurality of laser beams such that all of the different wavelengths(λ₁-λ_(X)) of the plurality of laser beams are provided to each of theplurality of optical output ports 241-1 to 241-Y of the opticalmarshalling module 233. Therefore, it should be understood that theoptical marshalling module 233 operates to provide light at all of thedifferent wavelengths (λ₁-λ_(X)) of the plurality of laser beams to eachone of the optical output ports 241-1 to 241-Y of the opticalmarshalling module 233, as indicated in FIG. 2B. In this manner, for thelaser chip 205, each one of the optical output ports 241-1 to 241-Y ofthe optical marshalling module 233 provides a corresponding one of aplurality of multi-wavelength laser outputs MWL-1 to MWL-Y.

In some embodiments, the optical marshalling module 233 is configured tomaintain a polarization of each of the plurality of laser beams betweenthe plurality of optical input ports 239-1 to 239-X of the opticalmarshalling module 233 and the plurality of optical output ports 241-1to 241-Y of the optical marshalling module 233. Also, in someembodiments, the optical marshalling module 233 is configured such thateach of the plurality of optical output ports 241-1 to 241-Y of theoptical marshalling module 233 receives a similar amount of opticalpower of any given one of the plurality of laser beams within a factorof five. In other words, in some embodiments, the amount of light of agiven wavelength, i.e., one of the different wavelengths (λ₁-λ_(X)),that is provided by the optical marshalling module 233 to a particularone of the optical output ports 241-1 to 241-Y is the same within afactor of five to the amount of light of the given wavelength that isprovided by the optical marshalling module 233 to others of the opticaloutput ports 241-1 to 241-Y. It should be understood that the factor offive mentioned above is an example embodiment. In other embodiments, thefactor of five mentioned above can be changed to a factor of anothervalue, such as to a factor of two, or three, or four, or six, etc., orto any other value in between or less than or greater than. The point tobe understood is that the optical marshalling module 233 can beconfigured to control the amount of light of a given wavelength that isprovided to each of the optical output ports 241-1 to 241-Y of theoptical marshalling module 233, and in turn can be configured to controla uniformity of the amount of light of a given wavelength provided toeach of the optical output ports 241-1 to 241-Y of the opticalmarshalling module 233.

In the example embodiment, of FIG. 2B, the optical marshalling module233 is defined as a separate component attached to the substrate 230.Therefore, it should be understood that in the example embodiment of thelaser chip 205, the laser source 231 and the optical marshalling module233 are physically separate components. It should be understood that invarious embodiments the optical marshalling module 233 can beattached/mounted to the substrate 230 using essentially any knownelectronic packaging process. Also, in some embodiments, the opticalmarshalling module 233 is configured as a non-electrical component,i.e., as a passive component, and can be attached/mounted to thesubstrate 230 using techniques that do not involve establishment ofelectrical connections between the optical marshalling module 233 andthe substrate 230, such as by use of an epoxy or other type of adhesivematerial. In some embodiments, rather than being defined as a separatecomponent, the optical marshalling module 233 can be integrated within aPLC on a chip that includes other components in addition to the opticalmarshalling module 233. In some embodiments, both the opticalmarshalling module 233 and the laser source 231 are implemented togetherwithin a same PLC.

In some embodiments, the laser source 231 is aligned with the opticalmarshalling module 233 to direct the plurality of laser beamstransmitted from the optical outputs 237-1 to 237-X of the laser source231 into respective ones of the optical input ports 239-1 to 239-X ofthe optical marshalling module 233. In some embodiments, the opticalmarshalling module 233 is positioned spaced apart from the laser source231. In some embodiments, the optical marshalling module 233 ispositioned in contact with the laser source 231. And, in someembodiments, a portion of the optical marshalling module 233 ispositioned to overlap a portion of the laser source 231. In the exampleembodiment of the laser chip 205 as shown in FIG. 2B, the opticalmarshalling module 233 is positioned spaced apart from the laser source231, and an optical waveguide 243 is positioned between the laser source231 and the optical marshalling module 233. The optical waveguide 243 isconfigured to direct the plurality of laser beams from the laser source231 into respective ones of the plurality of optical input ports 239-1to 239-X of the optical marshalling module 233, as indicated by lines245-1 to 245-X.

In various embodiments, the optical waveguide 243 can be formed ofessentially any material through which light can be channeled from anentry location on the optical waveguide 243 to an exit location on theoptical waveguide 243. For example, in various embodiments, the opticalwaveguide 243 can be formed of glass, SiN, SiO2, germanium-oxide, and/orsilica, among other materials. In some embodiments, the opticalwaveguide 243 is configured to maintain a polarization of the pluralityof laser beams between the laser source 231 and the optical marshallingmodule 233. In some embodiments, the optical waveguide 243 includes (X)optical conveyance channels, where each optical conveyance channelextends from a respective one of the optical output ports 237-1 to 237-Xof the laser source 231 to a respective one of the optical input ports239-1 to 239-X of the optical marshalling module 233. In someembodiments, each of the (X) optical conveyance channels of the opticalwaveguide 243 has a substantially rectangular cross-section in a planenormal to a direction of propagation of the laser beam, i.e., normal tothe x-direction as shown in FIG. 2B, which serves to maintain apolarization of the laser beam as it propagates from the laser source231 to the optical marshalling module 233.

In the example embodiment of FIG. 2B, the optical waveguide 243 isdefined as a separate component attached to the substrate 230.Therefore, it should be understood that in the example embodiment of thelaser chip 205, the laser source 231, the optical waveguide 243, and theoptical marshalling module 233 are physically separate components. Itshould be understood that in various embodiments the optical waveguide243 can be attached/mounted to the substrate 230 using essentially anyknown electronic packaging process. Also, in some embodiments, theoptical waveguide 243 is configured as a non-electrical component, i.e.,as a passive component, and can be attached/mounted to the substrate 230using techniques that do not involve establishment of electricalconnections between the optical waveguide 243 and the substrate 230,such as by use of an epoxy or other type of adhesive material. In someembodiments, rather than being defined as a separate component, theoptical waveguide 243 can be integrated within a PLC on a chip thatincludes other components in addition to the optical waveguide 243. Insome embodiments, laser source 231, the optical waveguide 243, and theoptical marshalling module 233 are implemented together within a samePLC.

In some embodiments, the laser chip 205 includes a thermal spreadercomponent disposed proximate to the laser source 231. The thermalspreader component is configured to spread a thermal output of theplurality of lasers 235-1 to 235-X to provide substantial uniformity intemperature-dependent wavelength drift among the plurality of lasers235-1 to 235-X. In some embodiments, the thermal spreader component isincluded within the laser source 231. In some embodiments, the thermalspreader component is included within the substrate 230. In someembodiments, the thermal spreader component is defined separate fromeach of the laser source 231, the optical marshalling module 233, andthe substrate 230. In some embodiments, the thermal spreader componentis included within the optical marshalling module 233, with the thermalspreader component portion of the optical marshalling module 233physically overlapping the laser source 231. In some embodiments, thethermal spreader component is included within the optical waveguide 243,with the thermal spreader component portion of the optical waveguide 243physically overlapping the laser source 231. In various embodiments, thethermal spreader component is formed of a thermally conductive material,such as a metallic material by way of example. In some embodiments, thethermal spreader component can incorporate an element configured toactively transfer heat away from the plurality of lasers 235-1 to 235-X,such as a thermoelectric cooler by way of example. Also, in someembodiments, the thermal spreader component is formed to have asufficient bulk mass so as to function as a heat sink for heat emanatingfrom the plurality of lasers 235-1 to 235-X of the laser source 231.Additional description of various embodiments of the laser chip 205 isprovided in U.S. patent application Ser. No. 15/650,586, which isincorporated in its entirety herein by reference, and in U.S. patentapplication Ser. No. 16/194,250, which is incorporated in its entiretyherein by reference.

FIG. 2C shows an example architectural diagram of the TeraPHY chip 203,in accordance with some embodiments. In the example of FIG. 2C, theTeraPHY chip 203 includes processor and memory transceiver banks 251, aprocessor 253, a memory bank 255, and independent transceiver test sites257. FIG. 2C also shows an enlarged view of an example transmitter bank251A that is formed within the processor and memory transceiver banks251. The example transmitter bank 251A includes a optical input 259 forreceiving laser light from the laser chip 205. In some embodiments, theoptical input 259 is an optical grating coupler. The transmitter bank251A also includes an optical waveguide 261 that extends from theoptical input 259 to an optical output 263 of the transmitter bank 251A.In some embodiments, the optical output 263 is an optical gratingcoupler. The optical waveguide 261 passes through a series of opticaltransmitters formed within the transmitter bank 251A. The exampletransmitter bank 251A includes eleven optical transmitters.

FIG. 2C shows an enlarged view of an example optical transmitter 265.Within the optical transmitter 265, the optical waveguide 261 passesby/around a ring resonator of microring modulator 267. Light modulationprovided by the microring modulator 267 is controlled by a modulatordriver circuit 269. The modulator driver circuit 269 controls themicroring modulator 267 to generate modulated laser light thatcorresponds to an imprinting of an electrical data communication streamonto continuous wave laser light. The modulated laser light exits themicroring modulator 267 through the optical waveguide 261 and continueson to the optical output 263 of the transmitter bank 251A. The opticaltransmitter 265 also includes a tuning controller circuit 271 configuredand connected to control a temperature of the microring modulator 267 inorder to operate the microring modulator 267 at a specific resonantwavelength. In this manner, the modulated laser light generated by themicroring modulator 267 is at the specific resonant wavelength. Theoptical transmitter 265 also includes backend digital circuitry 273 tosupport operation of the various electrical components within theoptical transmitter 265. The optical transmitter 265 also includes adrop port photodetector 275 that is optically coupled to the microringmodulator 267 to provide for detection and measurement ofwavelength-specific light absorption within the ring resonator of themicroring modulator 267.

FIG. 2C also shows an enlarged view of an example optical receiver bank251B that is formed within the processor and memory transceiver banks251. The optical receiver bank 251B includes multiple optical receivers,each configured and connected to receive modulated laser light anddemodulate the received modulated laser light to generate acorresponding digital data communication stream. FIG. 2C shows anenlarged view of one of the optical receivers 276. The optical receiver276 includes an optical input 277 for receiving modulated laser light.In some embodiments, the optical input 277 is an optical gratingcoupler. The optical input 277 is connected through a correspondingoptical waveguide 279 to a photodetector 281. The photodetector 281 iscontrolled and operated to provide wavelength-specific detection oflight coming in through the optical waveguide 279. The optical receiver276 also includes a receiver circuit 283 configured and connected togenerate a digital data communication stream that corresponds to theincoming stream of modulated light as detected by the photodetector 281.The optical receiver 276 also includes backend digital circuitry 285 tosupport operation of the various electrical components within theoptical receiver 276. In the example of FIG. 2C, the optical receiverbank 251B includes eleven separate optical receivers 276. In someembodiments, the TeraPHY chip 203 can be configured as described in Sun,Chen, et al. “Single-chip microprocessor that communicates directlyusing light.” Nature 528.7583 (2015): 534, which is incorporated in itsentirety herein by reference for all purposes.

FIG. 2D shows an example schematic diagram of the TeraPHY chip 203, inaccordance with some embodiments. The TeraPHY chip 203 includes anelectrical PHY specification 286. In some embodiments, the electricalPHY specification 286 is an Advance Interface Bus by Intel. In someembodiments, the electrical PHY specification 286 includes a HighBandwidth Memory (HBM) and Kandou Bus for serialization/deserializationof data. The electrical PHY specification 286 is interfaced with anoptical PHY specification 287 through glue logic 289. The optical PHYspecification 287 includes a number of pairs of optical transmitters(Tx) and optical receivers (Rx). The glue logic 289 includes cross-barswitches and other circuitry as needed to interface the electrical PHYspecification 286 with the optical PHY specification 287. In someembodiments, the optical transmitters (Tx) and optical receivers (Rx)are combined in pairs, with each Tx/Rx pair forming an opticaltransceiver. The optical transmitters (Tx) and optical receivers (Rx)are optically connected to an optical fiber array 290. The optical fiberarray 290 provides for attachment of respective optical fibers to eachof the optical transmitters (Tx) and optical receivers (Rx) in theoptical PHY specification 287. In various embodiments, the opticalfibers can be optically connected to the optical transmitters (Tx) andoptical receivers (Rx) through vertical optical grating couplers, edgeoptical couplers, or essentially any other type of optical couplingdevice. The TeraPHY chip 203 also includes management circuits 291 andgeneral purpose input/output (GPIO) components 292 for communicatingelectrical data signals to and from the TeraPHY chip 203. In variousembodiments, the GPIO components 292 can include Serial PeripheralInterface (SPI) components and/or another type of component to enableoff-chip data communication. It should be understood that the TeraPHYchip 203 can also include many other circuits, such as memory (e.g.,SRAM), a CPU, analog circuits, or any other circuit that can be designedin CMOS.

FIG. 2E shows an example schematic diagram of chip-to-chip optical datacommunication, in accordance with some embodiments. FIG. 2E shows anexample optical transmitter bank 351 within a first chip (chip 1)operating to modulate five different wavelengths of continuous wavelaser light to in turn generate five modulated light data streams, whereeach modulated light data stream corresponds to an input electrical datastream. In some embodiments, the example optical transmitter bank 351represents components within the TeraPHY chip 203. The opticaltransmitter bank 351 includes five ring resonators 353(1)-353(5)respectively controlled by five modulator drivers 355(1)-355(5). Each ofthe five ring resonators 353(1)-353(5) has a corresponding resistivethermal tuner (heater) 357(1)-357(5) that is controlled to operate thecorresponding ring resonators 353(1)-353(5) at a prescribed opticalwavelength. The thermal tuner 357(1) controls the ring resonator 353(1)to operate at the optical wavelength λ1. The thermal tuner 357(2)controls the ring resonator 353(2) to operate at the optical wavelengthλ2. The thermal tuner 357(3) controls the ring resonator 353(3) tooperate at the optical wavelength λ3. The thermal tuner 357(4) controlsthe ring resonator 353(4) to operate at the optical wavelength λ4. Thethermal tuner 357(5) controls the ring resonator 353(5) to operate atthe optical wavelength λ5. The thermal tuners 357(1)-357(5) arecontrolled by a ring tuning control circuit 358.

Laser light that includes the five wavelengths λ1 to λ5 is transmittedfrom the laser chip 205 through the optical waveguide 213 to the opticalport (optical grating coupler) 359 and through an optical waveguide 361.The optical waveguide 361 extends past each of the ring resonators353(1)-353(5). As the laser light travels through the optical waveguide361 past a given ring resonators 353(1)-353(5), the wavelengths λ1 to λ5of the laser light optically couple into the ring resonators353(1)-353(5) based on the resonant wavelengths at which the ringresonators 353(1)-353(5) are operated. In this manner, wavelength λ1couples into ring resonator 353(1). Wavelength λ2 couples into ringresonator 353(2). Wavelength λ3 couples into ring resonator 353(3).Wavelength λ4 couples into ring resonator 353(4). Wavelength λ5 couplesinto ring resonator 353(5).

The modulator driver 355(1) receives an electrical data communicationstream b0 as an input. The modulator driver 355(2) receives anelectrical data communication stream b1 as an input. The modulatordriver 355(3) receives an electrical data communication stream b2 as aninput. The modulator driver 355(4) receives an electrical datacommunication stream b3 as an input. The modulator driver 355(5)receives an electrical data communication stream b4 as an input. Themodulator drivers 355(1)-335(5) operate to modulate the light coupledinto the respective ring resonators 353(1)-353(5) to respectivelygenerate modulated light streams representing the input electrical datacommunication streams b0-b4, respectively. The modulated light streamstravel on through the optical waveguide 361 and through an opticaloutput port 363 (optical grating coupler). The modulator drivers355(1)-335(5) operate in accordance with clock signals generated by aclock distribution circuit 365.

The five modulated light streams travel from the optical output port 363through an optical waveguide 367 to a second chip (chip 2) in which anexample optical receiver bank 369 operates to demodulate the fivemodulated light streams of different wavelengths λ1 to λ5 to in turngenerate five electrical data communication streams that match the fiveelectrical data communication streams b0-b4. The five modulated lightstreams travel from the optical waveguide 367 through an optical inputport 371 (optical grating coupler) and into an optical waveguide 373.

The optical receiver bank 369 includes five ring resonators375(1)-375(5) respectively connected to five receiver circuits377(1)-377(5). Each of the five ring resonators 375(1)-375(5) has acorresponding resistive thermal tuner (heater) 379(1)-379(5) that iscontrolled to operate the corresponding ring resonators 375(1)-375(5) ata prescribed optical wavelength. The thermal tuner 379(1) controls thering resonator 375(1) to operate at the optical wavelength λ1. Thethermal tuner 379(2) controls the ring resonator 375(2) to operate atthe optical wavelength λ2. The thermal tuner 379(3) controls the ringresonator 375(3) to operate at the optical wavelength λ3. The thermaltuner 379(4) controls the ring resonator 375(4) to operate at theoptical wavelength λ4. The thermal tuner 379(5) controls the ringresonator 375(5) to operate at the optical wavelength λ5. The thermaltuners 379(1)-379(5) are controlled by a ring tuning control circuit381.

The optical waveguide 373 extends past each of the ring resonators375(1)-375(5). As the five modulated light streams travel through theoptical waveguide 373 past the ring resonators 375(1)-375(5), thewavelengths λ1 to λ5 of the laser light optically couple into the ringresonators 375(1)-375(5) based on the resonant wavelengths at which thering resonators 375(1)-375(5) are operated. In this manner, wavelengthλ1 couples into ring resonator 375(1). Wavelength λ2 couples into ringresonator 375(2). Wavelength λ3 couples into ring resonator 375(3).Wavelength λ4 couples into ring resonator 375(4). Wavelength λ5 couplesinto ring resonator 375(5).

The receiver circuit 377(1) generates the electrical data communicationstream b0 as an output based on the light of wavelength λ1 coupled intothe ring resonator 375(1) from the optical waveguide 373. The receivercircuit 377(2) generates the electrical data communication stream b1 asan output based on the light of wavelength λ2 coupled into the ringresonator 375(2) from the optical waveguide 373. The receiver circuit377(3) generates the electrical data communication stream b2 as anoutput based on the light of wavelength λ3 coupled into the ringresonator 375(3) from the optical waveguide 373. The receiver circuit377(4) generates the electrical data communication stream b3 as anoutput based on the light of wavelength λ4 coupled into the ringresonator 375(4) from the optical waveguide 373. The receiver circuit377(5) generates the electrical data communication stream b4 as anoutput based on the light of wavelength λ5 coupled into the ringresonator 375(5) from the optical waveguide 373. The receiver circuits377(1)-377(5) operate in accordance with clock signals generated by aclock detection and redistribution circuit 383.

FIG. 2F shows an example transceiver macro implemented within theTeraPHY chip 203, in accordance with some embodiments. The transceivermacro includes Glue Logic Interfaces (Glue I/F) that include the digitallogic required to tie the Optical PHY 287 (Tx and Rx) to the rest of theTeraPHY chip 203. The Glue I/F can include the electrical PHY 286 on theTeraPHY chip 203. The transceiver macro also includes a Phase-LockedLoop Up (PLLU) and a Phase-Locked Loop Down (PLLD). The transceivermacro also includes reference clocks (Ref Clks), which are electricalclock signals used to synchronize operations within the transceivermacro. The transceiver macro also includes a Clock Spine, also referredto as a Clock Tree or a Clock Distribution. The Clock Spine is a set ofCMOS circuits that distribute the clock generated by the PLLU/PLLD tothe Tx Slices and Rx Slices in the transceiver macro so that operationsare appropriately synchronized. A laser input (Laser) fiber-to-chipcoupling point (e.g., optical grating coupler, optical edge coupler,etc.) is provided for the transceiver macro. A transmitter output (TxOut) fiber-to-chip coupling point (e.g., optical grating coupler,optical edge coupler, etc.) is provided for the transceiver macro. Areceiver input (Rx In) fiber-to-chip coupling point (e.g., opticalgrating coupler, optical edge coupler, etc.) is provided for thetransceiver macro. The transceiver macro also includes an numberTransmitter Slices (Tx Slice). The Tx Slice is a set of circuits thatmake up the transmit function. Tx Slice components include clockdistribution to the channels (such as to channels b0 to b4 shown in FIG.2E), modulator drivers, modulators (the ring resonators), thermaltuners, and the ring tuning control. The transceiver macro also includesa number of Receiver Slices (Rx Slice). The Rx Slice is a set ofcircuits that make up the receive function. Rx Slice components includedetection and redistribution to the electrical data communicationchannels (such as to b0 to b4 shown in FIG. 2E), receivers (e.g., CMOScircuits including components such as transimpedance amplifiers, etc.),photodetectors (the ring resonators), and ring tuning control. Invarious embodiments, the Tx Slices and the Rx Slices in the TeraPHY chip203 can be implemented in different ways. Some example Tx Slice and RxSlice implementations are described in Akhter, Mohammad Shahanshah, etal. “WaveLight: A Monolithic Low Latency Silicon-Photonics CommunicationPlatform for the Next-Generation Disaggregated Cloud Data Centers.” 2017IEEE 25th Annual Symposium on High-Performance Interconnects (HOTI).IEEE, 2017, which is incorporated herein by reference in its entiretyfor all purposes.

Arrayed optical waveguide gratings (AWG) are commonly used as optical(de)multiplexers in wavelength division multiplexed (WDM) systems.Passive AWG's include of an array of optical waveguides of differentlengths which determine the frequency channelization of the device.Active AWG's add active thermal tuning to each optical waveguide inorder to finely tune the frequency channelization response of the deviceand stabilize the frequency channelization response against process andtemperature variations.

The use of passive AWG's as filtering elements in dense WDM systems ismade difficult by process and temperature variations which can cause ashift in AWG channel characteristics. These issues necessitate use ofeither a first option that includes a WDM system with tunable lasersources that can adapt to the shift in AWG channel characteristics, or asecond option that includes a thermally-stabilized AWG that adapts itsfrequency characteristics to the dense WDM wavelength grid. Both of theabove-mentioned first and second options increase the overall cost andenergy footprint of the system. Therefore, it is of interest to haveadditional options for managing effects of process and temperaturevariations in dense WDM systems. In this regard, the SmartDistribuTORmodules 111-1 through 111-K provide a small (hence cost-effective) andlow-energy adaptive optical multiplexer/demultiplexer (mux/demux)solution.

FIG. 3 shows a schematic of one SmartDistribuTOR module 111-x, (111-xcorresponds to any one of 111-1 through 111-K) with an example downlinkfiber wavelength plan for the downlink optical fiber 115 and an exampleuplink fiber wavelength plan for the uplink optical fiber 117, inaccordance with some embodiments. As shown in FIG. 3 , theSmartDistribuTOR module 111-x enables splitting and aggregation ofwavelengths on multiple optical channels within the optical fiber tomultiple optical fibers. In some embodiments, dense WDM can be used topack a large number of optical channels and increase the number ofservers reachable via a single pair of optical fibers, e.g., via thedownlink optical fiber 115 and the uplink optical fiber 117.

In some embodiments, the downlink optical fiber 115 and the uplinkoptical fiber 117 can be connected to the duplex connector 113 exposedat a surface of the SmartDistribuTOR module 111-x. The duplex connector113 functions to enable connection of two external optical fibers to thedownlink optical fiber 115 and the uplink optical fiber 117,respectively. The example embodiment of FIG. 3 shows eight opticalchannels Ch1 to Ch8 on the downlink optical fiber 115, with onemodulated wavelength 301(1)-301(8) per optical channel, respectively,and with one continuous wave wavelength 303(1)-303(8) per opticalchannel, respectively. Also, the example embodiment of FIG. 3 showseight optical channels Ch1 to Ch8 on the uplink optical fiber 117, withone modulated wavelength 305(1)-305(8) per optical channel,respectively. In some embodiments, each modulated wavelength301(1)-301(8) and 305(1)-305(8) can carry 100 Gbps of data, by way ofexample. In some embodiments, the wavelengths conveyed to and/or fromthe SmartDistribuTOR module 111-x are in the O-band wavelength range. Insome embodiments, the wavelengths conveyed to and/or from theSmartDistribuTOR module 111-x are in the C-band or L-band wavelengthrange.

FIG. 3 also shows the tunable optical DEMUX block 119 within theSmartDistribuTOR module 111-x, in accordance with some embodiments. Thetunable optical DEMUX block 119 is configured to split wavelengths onthe multiple optical channels Ch1 to Ch8 within the downlink opticalfiber 115 to multiple optical waveguides/fibers 123(1) to 123(8),respectively. Each of the multiple optical waveguides/fibers123(1)-123(8) is connected to a respective duplex connector307(1)-307(8) exposed at a surface of the SmartDistribuTOR module 111-x.The duplex connectors 307(1)-307(8) function to enable connection of theoptical waveguides/fibers 123(1)-123(8) to corresponding externaloptical fibers.

FIG. 3 also shows the tunable optical MUX block 121 within theSmartDistribuTOR module 111-x, in accordance with some embodiments. Thetunable optical MUX block 121 is configured to aggregate multiplewavelengths from multiple optical waveguides/fibers 125(1)-125(8) ontothe multiple optical channels Ch1 to Ch8, respectively, within theuplink optical fiber 117. Each of the multiple optical waveguides/fibers125(1)-125(8) is connected to a respective one of the duplex connectors307(1)-307(8) exposed at the surface of the SmartDistribuTOR module111-x. The duplex connectors 307(1)-307(8) function to enable connectionof the optical waveguides/fibers 125(1)-125(8) to corresponding externaloptical fibers.

FIG. 4 shows a schematic of the tunable optical DEMUX block 119 withinthe SmartDistribuTOR module 111-x, in accordance with some embodiments.The tunable optical DEMUX block 119 includes an input optical waveguide401. In various embodiments, the input optical waveguide 401 can be anoptical fiber or a solid optical waveguide structure formed of silicon,glass, or other suitable optical waveguide material. The input opticalwaveguide 401 is coupled to receive light incoming from the downlinkoptical fiber 115. In some embodiments, the polarization of light cominginto the tunable optical DEMUX block 119 is unknown, which necessitatesa downlink polarization management block 403 to be integrated togetherwith the tunable optical DEMUX block 119 on the same die. In the tunableoptical DEMUX block 119, polarization management/control is needed onlyon the input optical waveguide 401, as shown by the downlinkpolarization management block 403. In some embodiments, the downlinkpolarization management block 403 includes a polarization splittingoptical grating. In some embodiments, the downlink polarizationmanagement block 403 includes a polarization independent optical couplerfollowed by a polarization splitter-rotator. In some embodiments, afterpolarization splitting is done by the downlink polarization managementblock 403, the two paths (polarizations) are combined into a singleoptical waveguide 405 using a thermally controlled Mach-Zehnderinterferometer tuned to maximize the optical power on each wavelength atits output.

The downlink polarization management block 403 is electrically connectedto an embedded master controller 421, as indicated by a connection 409.The embedded master controller 421 is configured to control operation ofthe downlink polarization management block 403 by directing transmissionof control signals through the connector 409. The embedded mastercontroller 421 is also configured to receive monitored/measured signalsfrom the downlink polarization management block 403 through theconnection 409. It should be understood that the connection 409 caninclude multiple independent electrical conductors and/or electricaltraces in various embodiments.

The tunable optical DEMUX block 119 includes a tunable optical ringresonator filterbank 407 that includes (N) optical ring resonatorfilters 413(1)-413(N) corresponding to Channel 1 through Channel N,respectively. Each of the optical ring resonator filters 413(1)-413(N)includes at least one ring resonator 417(1)-417(N), respectively,arranged next to the optical waveguide 405 to define a desired channeltransfer function. In some embodiments, each of the optical ringresonator filters 413(1)-413(N) includes at least one embedded heatingelement 415(1)-415(N), respectively, that is connected and configuredfor control by an embedded electronic control loop 419(1)-419(N),respectively. In some embodiments, the optical ring resonator filters413(1)-413(N) are designed in a Complementary Metal-Oxide Semiconductor(CMOS) Silicon on Insulator (SOI) process, and are integratedmonolithically on the same die as the transistors that comprise thecircuitry of the embedded electronic control loops 419(1)-419(N). Insome embodiments, each of the optical ring resonator filters413(1)-413(N) includes a respective embedded photo-detector, which isused/operated as a sensor for wavelength lock.

In some embodiments, a given ring resonator 417(1)-417(N) of acorresponding optical ring resonator filter 413(1)-413(N) is heated bydriving electrical current directly through the silicon body of the ringresonator 417(1)-417(N). Because the ring resonator 417(1)-417(N) isresistive, the ring resonator 417(1)-417(N) will heat up when electricalcurrent is driven through it. In these embodiments, a change in theelectrical current that is driven through the ring resonator417(1)-417(N) will occur due to photon-induced carrier generation in thering resonator 417(1)-417(N). This change in the electrical current dueto photon-induced carrier generation in the ring resonator 417(1)-417(N)can be used to sense the proximity of laser wavelength to the resonancewavelength of the ring resonator 417(1)-417(N). In some embodiments,when a given optical ring resonator filter 413(1)-413(N) is heated bydriving electrical current directly through the silicon body of thecorresponding ring resonator 417(1)-417(N), the embedded heating element415(1)-415(N) is not disposed and/or used within the given optical ringresonator filter 413(1)-413(N).

In some embodiments, the ring resonator 417(1)-417(N) is a p-i-n dopedtype of ring structure with the p and n region being the contact regionsused to sense the generated photon-induced carriers. In theseembodiments, the embedded heating element 415(1)-415(N) can be aseparate structure formed outside of the ring resonator 417(1)-417(N).When the ring resonator 417(1)-417(N) is defined as the p-i-n doped typeof ring structure, the ring resonator 417(1)-417(N) can be reversedbiased to sweep the generated photon-induced charge carriers into asensing circuit that then drives the embedded electronic control loop419(1)-419(N) to lock the optical ring resonator filter 413(1)-413(N) toa particular wavelength. Also, in some embodiments, the silicon body ofthe ring resonator 417(1)-417(N) has defect states that enablegeneration of photon-induced charge carriers, which is enough to sensethe optical power in the ring resonator 417(1)-417(N) without embeddinga photodetector.

In some embodiments, each embedded electronic control loop 419(1)-419(N)includes an analog front-end which converts sensed electrical currentinto a voltage. Also, each embedded electronic control loop419(1)-419(N) includes a digitizer that generates a digitalrepresentation of the voltage output by the analog front-end. Also, eachembedded electronic control loop 419(1)-419(N) includes control looplogic and a digital-to-analog converter that outputs electrical currentto drive the embedded heating element 415(1)-415(N) or to driveelectrical current directly through the silicon body of the ringresonator 417(1)-417(N). In some embodiments, the embedded mastercontroller 421 controls each embedded electronic control loop419(1)-419(N) through respective electrical connections 423(1)-423(N) toensure locking of each optical ring resonator filter 413(1)-413(N) to adesired wavelength in the dense WDM spectrum. The resonance wavelengthsof the ring resonators 417(1)-417(N) are controlled such that theoptical ring resonator filters 413(1)-413(N) optically couple aparticular wavelength onto a corresponding output optical waveguide425(1)-425(N), thereby providing the modulated wavelengths 301(1)-301(N)on the channels Ch1 to ChN, respectively.

FIG. 5 shows a schematic of the tunable optical MUX block 121 within theSmartDistribuTOR module 111-x, in accordance with some embodiments. Thetunable optical MUX block 121 includes N input optical waveguides501(1)-501(N). In various embodiments, each of the input opticalwaveguides 501(1)-501(N) can be an optical fiber or a solid opticalwaveguide structure formed of silicon, glass, or other suitable opticalwaveguide material. Each of the input optical waveguides 501(1)-501(N)is coupled to receive light incoming from the multiple opticalwaveguides 125(1)-125(N). In some embodiments, the polarization of lightcoming into the tunable optical MUX block 121 is unknown, whichnecessitates a number N of polarization management blocks 503(1)-503(N)to be integrated together with the tunable optical MUX block 121 on thesame die. In the tunable optical MUX block 121, polarizationmanagement/control is provided for each of the input optical waveguides501(1)-501(N), as shown by the polarization management blocks503(1)-503(N). In some embodiments, each of the polarization managementblocks 503(1)-503(N) includes a polarization splitting optical grating.In some embodiments, each of the polarization management blocks503(1)-503(N) includes a polarization independent optical couplerfollowed by a polarization splitter-rotator. In some embodiments, afterpolarization splitting is done by the polarization management block503(1)-503(N), the two paths (polarizations) are combined into a singleoptical waveguide 505(1)-505(N) using a thermally controlledMach-Zehnder interferometer tuned to maximize the optical power on eachwavelength at its output.

Each polarization management block 503(1)-503(N) is electricallyconnected to an embedded master controller 509, as indicated byelectrical connections 507(1)-507(N). The embedded master controller 509is configured to control operation of the polarization management blocks503(1)-503(N) by directing transmission of control signals through theconnections 507(1)-507(N). The embedded master controller 509 is alsoconfigured to receive monitored/measured signals from the polarizationmanagement blocks 503(1)-503(N) through the connections 507(1)-507(N).It should be understood that each of the connections 507(1)-507(N) caninclude multiple independent electrical conductors and/or electricaltraces in various embodiments.

The tunable optical MUX block 121 includes a tunable optical ringresonator filterbank 511 that includes (N) optical ring resonatorfilters 513(1)-513(N) corresponding to Channel 1 through Channel N,respectively. Each of the optical ring resonator filters 513(1)-513(N)includes at least one ring resonator 517(1)-517(N), respectively,arranged next to a respective one of the optical waveguides505(1)-505(N) to define a desired channel transfer function. In someembodiments, each of the optical ring resonator filters 513(1)-513(N)includes at least one embedded heating element 515(1)-515(N),respectively, that is connected and configured for control by anembedded electronic control loop 519(1)-519(N), respectively. In someembodiments, the optical ring resonator filters 513(1)-513(N) aredesigned in a CMOS SOI process, and are integrated monolithically on thesame die as the transistors that comprise the circuitry of the embeddedelectronic control loops 519(1)-519(N). In some embodiments, each of theoptical ring resonator filters 513(1)-513(N) includes a respectiveembedded photo-detector, which is used/operated as a sensor forwavelength lock.

In some embodiments, a given ring resonator 517(1)-517(N) of acorresponding optical ring resonator filter 513(1)-513(N) is heated bydriving electrical current directly through the silicon body of the ringresonator 517(1)-517(N). Because the ring resonator 517(1)-517(N) isresistive, the ring resonator 517(1)-517(N) will heat up when electricalcurrent is driven through it. In these embodiments, a change in theelectrical current that is driven through the ring resonator517(1)-517(N) will occur due to photon-induced charge carrier generationin the ring resonator 517(1)-517(N). This change in the electricalcurrent due to photon-induced charge carrier generation in the ringresonator 517(1)-517(N) can be used to sense the proximity of laserwavelength to the resonance wavelength of the ring resonator517(1)-517(N). In some embodiments, when a given optical ring resonatorfilter 513(1)-513(N) is heated by driving electrical current directlythrough the silicon body of the corresponding ring resonator517(1)-517(N), the embedded heating element 515(1)-515(N) is notdisposed and/or used within the given optical ring resonator filter513(1)-513(N).

In some embodiments, the ring resonator 517(1)-517(N) is a p-i-n dopedtype of ring structure with the p and n region being the contact regionsused to sense the generated photon-induced charge carriers. In theseembodiments, the embedded heating element 515(1)-515(N) can be aseparate structure formed outside of the ring resonator 517(1)-517(N).When the ring resonator 517(1)-517(N) is defined as the p-i-n doped typeof ring structure, the ring resonator 517(1)-517(N) can be reversedbiased to sweep the generated photon-induced charge carriers into asensing circuit that then drives the embedded electronic control loop519(1)-519(N) to lock the optical ring resonator filter 513(1)-513(N) toa particular wavelength. Also, in some embodiments, the silicon body ofthe ring resonator 517(1)-517(N) has defect states that enablegeneration of photon-induced charge carriers, which is enough to sensethe optical power in the ring resonator 517(1)-517(N) without embeddingan actual photodetector.

In some embodiments, each embedded electronic control loop 519(1)-519(N)includes an analog front-end which converts sensed electrical currentinto a voltage. Also, each embedded electronic control loop519(1)-519(N) includes a digitizer that generates a digitalrepresentation of the voltage output by the analog front-end. Also, eachembedded electronic control loop 519(1)-519(N) includes control looplogic and a digital-to-analog converter that outputs electrical currentto drive the embedded heating element 515(1)-515(N) or to driveelectrical current directly through the silicon body of the ringresonator 517(1)-517(N). In some embodiments, the embedded mastercontroller 509 controls each embedded electronic control loop519(1)-519(N) through respective electrical connections 523(1)-523(N) toensure locking of each optical ring resonator filter 513(1)-513(N) to adesired wavelength in the dense WDM spectrum.

The tunable optical ring resonator filterbank 511 operates the (N)optical ring resonator filters 513(1)-513(N) to combine selected ones ofthe (N) modulated wavelengths 305(1)-305(N) received on the multipleoptical waveguides 125(1)-125(N) onto an output optical waveguide 521.In some embodiments, the tunable optical MUX block 121 can be controlledto combine all (N) modulated wavelengths 305(1)-305(N) onto the outputoptical waveguide 521. In some embodiments, the tunable optical MUXblock 121 can be controlled to combine less than all of the (N)modulated wavelengths 305(1)-305(N) onto the output optical waveguide521, where the particular ones of the modulated wavelengths305(1)-305(N) that are combined onto the output optical waveguide 521can be selected through control of the optical ring resonator filters513(1)-513(N) by way of the embedded master controller 509. The outputoptical waveguide 521 is optically connected to the uplink optical fiber117.

In some embodiments, the SmartDistribuTOR module 111-x is autonomous(self-managed) upon power-up. In some embodiments, the SmartDistribuTORmodule 111-x can be managed remotely through amicroprocessor/microcontroller embedded on the same die/chip or on thesame module board as the SmartDistribuTOR module 111-x. In variousembodiments, the SmartDistribuTOR module 111-x disclosed herein providesfor robust, temperature-variation-insensitive,process-variation-insensitive, and polarization-variation-insensitiveoptical multiplexing and demultiplexing for dense WDM systems. Invarious embodiments, the SmartDistribuTOR module 111-x can operate ineither the O-band wavelength range, the C-band wavelength range, or theL-band wavelength range. The SmartDistribuTOR module 111-x has lowenergy consumption and has a small area footprint on the die/chip. Invarious embodiments, the SmartDistribuTOR module 111-x is aself-adaptive system that does not require external control.

In some embodiments, the SmartDistribuTOR module 111-x disclosed hereinprovides a tunable optical multiplexer/demultiplexer based on tunableoptical ring resonator filterbank operation with embedded heaterscontrolled by an electronic control loop. In some embodiments, theelectronic control loop has a local per channel controller and globalmaster controller. In some embodiments, the electronic control loop isintegrated on the same die/chip as the optical ring resonators. In someembodiments, an embedded optical polarization management block iscoupled to the electronic control loop.

In some embodiments, the tunable optical ring resonator filterbank isconfigured to enable detection of the proximity of the resonance towavelength by way of charge carrier generation within the passive ringresonator filter. In some embodiments, the passive ring resonator filterhas an embedded heater. In some embodiments, the proximity of theresonance to wavelength is detected through a change in heaterelectrical current. In some embodiments, an embedded photodetector isprovided in a small portion/slice of the passive ring resonator filter.

In some embodiments, the SmartDistribuTOR module 111-x disclosed hereinprovides for tunable ring resonator multiplexing/demultiplexing in denseWDM systems to multiplex/demultiplex wavelengths to servers in a serverrack. In some embodiments, the SmartDistribuTOR module 111-x disclosedherein is located in a top region of the server rack. In someembodiments, the SmartDistribuTOR module 111-x provides for multi-ringper channel add/drop of wavelength(s) with embedded resonance control.

In current data-centers, servers are organized in racks. Each rackincludes a Top-of-Rack (TOR) switch, which connects the servers in therack to the rest of the data-center network (typically called the coreor the spine). Each server is connected to the TOR switch via coppercables. Optical pluggable transceivers connect the TOR switch with therest of the data-center network. Systems and methods are disclosedherein that utilize highly integrated electronic-photonic transceivertechnology to enable one or more direct optical links from thedata-center network to each server, without needing to have the opticalsource component, i.e., laser, in the server-side electro-opticalmodule. The server-side electro-optical module can be referred to as aReverb module.

FIG. 6 shows a schematic of a server-side electro-optical module 601(“Reverb”) within a server 600, in accordance with some embodiments. Theserver 600 represents any of the servers 1 through M shown in FIG. 1 .Also, the electro-optical module 601 represents any of theelectro-optical modules Rvb-1 through Rvb-M shown in FIG. 1 . In someembodiments, the electro-optical module 601 includes a Reverb chip 603and a SerDes chip 605. In some embodiments, the electro-optical module601 includes the Reverb chip 603 without the SerDes chip 605. In someembodiments, the Reverb chip 603 includes optical components andelectrical components integrated monolithically together on the samedie. In some embodiments, the Reverb chip 603 includes only opticalcomponents. In some embodiments, the electro-optical module 601 is anactive-optical-cable (AOC), where the optical fiber that connects theelectro-optical module 601 to the SmartDistribuTOR module 111-x in thesame rack is directly attached to the Reverb chip 603. In someembodiments, the Reverb chip 603 is optical fiber pigtailed andconnectorized at the edge of the electro-optical module 601.

The electro-optical module 601 couples to an optical fiber pair 607 andreceives and transmits optical signals on the optical fiber pair 607. Insome embodiments, the optical fiber pair 607 is terminated with aconnector 609, such as with an LC duplex connector or other suitabletype of optical fiber connector. A first optical fiber 607A of theoptical fiber pair 607 carries a modulated wavelength with downlink dataand one unmodulated (continuous wave (CW)) wavelength to the server 600on which the electro-optical module 601 is installed. A second opticalfiber 607B of the optical fiber pair 607 carries a modulated wavelengthwith uplink data from the server 600 on which the electro-optical module601 is installed to the data-center network. In some embodiments, theoptical fibers 607A, 607B of the optical fiber pair 607 are directlypigtailed to the Reverb chip 603 in the electro-optical module 601, soas to constitute an Active Optical Cable (AOC). In some embodiments, theReverb chip 603 is pigtailed and the pigtail is connectorized on aface-plate of the electro-optical module 601 with a connector, such aswith an LC duplex connector or other suitable type of optical fiberconnector.

The Reverb chip 603 is configured to receive the modulated downlinkwavelength and convert the received modulated downlink wavelength to anelectrical data stream, and provide the electrical data stream to theserver 600 through an electrical bus 611 and a network interface card613. The Reverb chip 603 is also configured to modulate the receivedunmodulated (CW) wavelength with uplink data traffic for transmissionfrom the server 600 on which the electro-optical module 601 is installedto the rest of the data-center network. The Reverb chip 603 receiveselectrical data communication signals from the server 600 through thenetwork interface card 613 an the electrical bus 611. The Reverb chip603 modulates the unmodulated CW wavelength to generate modulated lightthat conveys the data included in the electrical data communicationsignals received from the server 600. In some embodiments, the SerDeschip 605 operates to serialize parallel data received through theelectrical bus 611 from the server 600 in route to the Reverb chip 603.Also, in some embodiments, the SerDes chip 605 operates to deserializeserial data into parallel data for transmission through the electricalbus 611 and network interface card 613 to the server 600.

In some embodiments, the Reverb chip 603 is an electronic-photonic chipand includes both photonic components (optical couplers, opticalwaveguides, optical modulators, photodetectors, optical filters, etc.)and electronic components (transistors, electrical conductors, etc.). Insome embodiments in which the Reverb chip 603 is the electronic-photonicchip, the photonic components and the electronic components of theReverb chip 603 are integrated monolithically on the same die formed ina CMOS fabrication process. In some embodiments, the Reverb chip 603 isconfigured to include just the photonic components, while the SerDeschip 605 is configured to include the electronic components and circuitsthat interface and control the photonic Reverb chip 603. In someembodiments in which the Reverb chip 603 is the electronic-photonicchip, the Reverb chip 603 includes electronic circuitry that controls apolarization and a resonant wavelength of the photonic components withinthe Reverb chip 603. In some embodiments in which the Reverb chip 603 isthe electronic-photonic chip, the Reverb chip 603 includes additionalnon-retimed electronic interface circuitry (such as receivers, modulatordrivers, etc.). In some embodiments in which the Reverb chip 603 is theelectronic-photonic chip, the Reverb chip 603 also includes retimingelectronic circuits (serializer, deserializer, clock generators—phaselocked loop and clock-data-recovery loop, etc.).

FIG. 7 shows a schematic of the Reverb chip 603, in accordance with someembodiments. The Reverb chip 603 includes a downlink polarizationcontrol block 703, a downlink data receiver block 709, an uplink datamodulator block 711, and an electrical input/output (I/O) block 713. TheReverb chip 603 includes an optical waveguide 701 through which thedownlink modulated light 704 and the CW light 702 is received from theoptical fiber 607A. The downlink polarization control block 703 isoptically connected to receive the downlink modulated light 704 and theCW light 702 from the optical waveguide 701. In some embodiments, thedownlink polarization block 703 includes a polarization splittingoptical grating. In some embodiments, the downlink polarization block703 includes a polarization independent optical coupler followed by apolarization splitter-rotator. In some embodiments, after polarizationsplit in the downlink polarization block 703, the two paths(polarizations) are combined into a single optical waveguide 705 using athermally controlled Mach-Zehnder interferometer, tuned to maximize theoptical power on each optical wavelength at its output.

In some embodiments, the downlink data receiver block 709 opticallycouples to an optical output of the downlink polarization control block703. The downlink data receiver block 709 is configured to filter thedownlink modulated wavelength 704 and convert the filtered downlinkmodulated wavelength 704 into an electrical signal. The downlink datareceiver block 709 is also configured to pass the unmodulated (CW)wavelength 702 to the uplink data modulator block 711. The uplink datamodulator block 711 is configured to imprint an uplink electrical datastream on the unmodulated (CW) wavelength 702 to create an uplinkmodulated wavelength light signal 706. The uplink data modulator block711 is configured to transmit the uplink modulated wavelength lightsignal 706 through an optical waveguide 707 to the uplink optical fiber607B.

In some embodiments, the downlink data receiver block 709 includes oneor more resonant ring filters configured to drop one or more modulateddownlink data wavelengths to one or more corresponding photodetectors.In some embodiments, the corresponding photodetector is integrated inthe resonant ring filter. In some embodiments, the resonant ring filteris tuned to the modulated downlink data wavelengths using an embeddedheater. In some embodiments, the embedded heater of the resonant ringfilter is controlled by an embedded digital control loop which sensesthe amount of light that the resonant ring drops (or absorbs). In someembodiments, the digital control loop for the embedded heater of theresonant ring filter is placed on another CMOS chip in theelectro-optical module 601.

In some embodiments, the uplink data modulator block 711 includes one ormore resonant ring modulators. In some embodiments, the resonant ringmodulators of the uplink data modulator block 711 are tuned to one ormore CW wavelengths using embedded heaters. In some embodiments, theembedded heater of the resonant ring modulator is controlled by anembedded digital control loop which senses the amount of light that theresonant ring drops (or absorbs). In some embodiments, the digitalcontrol loop for the embedded heater of the resonant ring modulator isplaced on another CMOS chip in the electro-optical module 601.

In some embodiments, the electro-optical module 601 receives onemodulated wavelength and one CW wavelength on the downlink optical fiber607A, and modulates the received CW wavelength from the downlink opticalfiber 607A onto the uplink optical fiber 607B. In some embodiments, theelectro-optical module 601 receives multiple modulated wavelengths andmultiple CW wavelengths on the downlink optical fiber 607A, andmodulates the received CW wavelengths from the downlink optical fiber607A onto the uplink optical fiber 607B. In some embodiments, theelectro-optical module 601 is configured to receive optical signals frommultiple downlink optical fibers 607A and provide optical signals tomultiple uplink optical fibers 607B. In these embodiments, each of themultiple downlink optical fibers 607A conveys one or more modulatedwavelength(s) and one or more unmodulated CW wavelength(s) to theelectro-optical module 601, and each of the multiple uplink opticalfibers 607B conveys one or more modulated wavelength(s) from theelectro-optical module 601. In some embodiments, the wavelengthsconveyed to and/or from the electro-optical module 601 are in the O-bandwavelength range. In some embodiments, the wavelengths conveyed toand/or from the electro-optical module 601 are in the C-band or L-bandwavelength range.

FIG. 8 shows an example uplink and downlink wavelength plan per downlinkoptical fiber 607A and uplink optical fiber 607B, in accordance withsome embodiments. In some embodiments, dense wavelength divisionmultiplexing can be used to pack a large number of optical channels andincrease the number of servers reachable via a single uplink anddownlink optical fiber pair 607. The example embodiment of FIG. 8 showseight optical channels Ch1 to Ch8 on the downlink fiber 607A, with onemodulated wavelength 301(1)-301(8) per optical channel, respectively,and with one continuous wave wavelength 303(1)-303(8) per opticalchannel, respectively. Also, the example embodiment of FIG. 8 showseight optical channels Ch1 to Ch8 on the uplink fiber 607B, with onemodulated wavelength 305(1)-305(8) per optical channel, respectively. Insome embodiments, each modulated wavelength 301(1)-301(8) and305(1)-305(8) can carry 100 Gbps of data, by way of example. In variousembodiments, a passive or active optical multiplexer/demultiplexer, suchas the SmartDistribuTOR module 111-x, separates one or more channels tobe forwarded to the electro-optical module 601 in each server.

It should be understood that the electro-optical module 601 enableshigh-bandwidth, low-energy and low-cost optical connection from eachserver to the data-center network by leveraging advances inelectronic-photonic integration in CMOS and low-cost dense wavelengthdivision multiplexing (DWDM). Miniaturization of optical components instandard CMOS chips and temperature control of those components usingon-chip digital logic for auto-feedback loops enables a reliable,low-cost, and high-bandwidth system for connecting racks of servers.This interconnectivity of thousands of servers enables disaggregation ofcompute, memory, and storage resources across many racks, makingflexible real-time allocation of compute jobs across racks possible.

In various embodiments, the electro-optical module 601 provides forhaving no lasers in the servers 1 through M, because of continuous wavelaser light forwarding from the TORminator module 107 through theSmartDistribuTOR module 111-x to the electro-optical module 601 in theserver. The electro-optical module 601 also provides for a ubiquitousserver-side module in that any server module can work at any DWDMwavelength in the wavelength range of interest (e.g., O-band). Theelectro-optical module 601 also provides for operation over standardduplex single mode (SM) optical fiber pairs, with a single fiber pairconnection to server. The electro-optical module 601 also provides forscalability through parallel transmission and processing of differentwavelengths of light.

In some embodiments, the electro-optical module 601 does not have anonboard laser, but rather is configured to receive at least one CWwavelength and at least one modulated wavelength. The electro-opticalmodule 601 is configured to modulate the CW wavelength for uplink datatransmission. The electro-optical module 601 includes the Reverb chip603 that can include silicon-photonic components. In some embodiments,the Reverb chip 603 can include monolithically integrated transistorsand photonic components. In some embodiments, the Reverb chip 603 caninclude photonic resonant components with embedded heaters. In someembodiments, the Reverb chip 603 can include photonic resonantcomponents and embedded tuning circuits. In some embodiments, the Reverbchip 603 can include photonic resonant components and embedded tuningcircuits, along with photonic link transceivers (receivers and modulatordrivers). In some embodiments, the Reverb chip 603 can include photonicresonant components and embedded tuning circuits, along with photoniclink transceivers (receivers and modulator drivers), and a retimedinterface (serializer and deserializer). In some embodiments, the Reverbchip 603 can include photonic resonant components and embedded tuningcircuits, and photonic link transceivers (receivers and modulatordrivers), and a retimed interface (serializer and deserializer), and aclock and data-recover loop. In some embodiments, the Reverb chip 603includes active polarization control/combining in the Reverb chip 603.In some embodiments, the Reverb chip 603 includes a polarizationsplitting coupler. In some embodiments, the Reverb chip 603 includes apolarization independent coupler and a polarization splitter/rotator.

In some embodiments, the Reverb chip 603 includes one or more resonantfilters to drop the modulated downlink wavelengths. In some embodiments,the one or more resonant filters include passive, tunable ring filters.In some embodiments, the one or more resonant filters include active,tunable, ring-resonator-based photodetectors. In some embodiments, theReverb chip 603 includes one or more tunable resonant modulators tomodulate the received CW wavelengths for the uplink data.

FIG. 9 shows the TORminator system 100 implemented across multiple rackswithin a datacenter, in accordance with some embodiments. The example ofFIG. 9 corresponds to the TORminator system 100 example of FIG. 1 .Therefore, 128 servers (M=128) are distributed across 16 racks (K=16)901-1 to 901-16, with each rack including a separate SmartDistribuTORmodule 111-1 to 111-16 and 8 servers (N=8). One rack (rack 901-1 in theexample of FIG. 9 ) includes the EOR/MOR switch linecard 101 thatservices all 16 racks 901-1 to 901-16. In this configuration, theTORminator system 100 provides for optical data communication betweenthe EOR/MOR switch linecard 101 and each of the 128 servers in the 16racks.

It should be understood that the TORminator system 100 disclosed hereincreates large pools of highly interconnected servers by leveragingadvances in electronic-photonic integration in CMOS and low-cost densewavelength division multiplexing (DWDM) in the O-band wavelength range.Miniaturization of optical components in standard CMOS chips and robustlock control of those components enable a reliable, low-cost, andhigh-bandwidth TORminator system 100 for optically connecting multipleracks of servers. It should be understood that the TORminator system 100disclosed herein can be scaled to interconnect thousands of servers.This interconnectivity of thousands of servers enables disaggregation ofcompute, memory, and storage resources across many racks, makingflexible real-time allocation of compute jobs across racks possible.

In various embodiments, the TORminator system 100 disclosed hereinprovides for low optical fiber count due to efficient wavelengthmux-demux for dense wavelength-division multiplexing in the O-band(O-DWDM).

In various embodiments, the TORminator system 100 disclosed hereinprovides for optical communication between multiple servers withouthaving lasers in the multiple servers, because the laser lightforwarding from the TORminator module 107 through the SmartDistribuTORmodules 111-x to the servers. The TORminator system 100 also provides aubiquitous server-side electro-optical module 601 that can work at anyO-DWDM wavelength. The TORminator system 100 also provides for operationover standard duplex single mode optical fiber pairs. In someembodiments, the TORminator system 100 also provides a low-power systemwith uncooled lasers within the laser chip 205 in the TORminator module107 on the EOR/MOR switch linecard 101. The TORminator system 100 alsoprovides a pluggable architecture with options for in-packageintegration of the TeraPHY chip 203 with a switch chip (ASIC) within therack switch 103. The TORminator system 100 also provides for scalabilitythrough parallel transmission and processing of different wavelengths oflight.

In some embodiments, the TORminator system 100 includes the TORminatormodule 107 in electrical data communication with the rack switch 103,and the TORminator module 107 in optical data communication with theSmartDistribuTOR module 111-x, and the SmartDistribuTOR module 111-x inoptical data communication with the electro-optical modules 601 ofservers. The TORminator system 100 provides for forwarding of laserlight to the servers for optical uplink of data (even without thetop-of-the-rack optical mux/demux). The TORminator system 100 alsoprovides for multiple channels per optical fiber (one or more for eachserver). The TORminator system 100 also provides for no laser or opticalamplifier at the server side.

In some embodiments, the TORminator module 107 includes the TeraPHY chip203 and the laser chip 205. In some embodiments, the TORminator module107 can provide the SOA array chip 207 on the downlink. In someembodiments, the TORminator module 107 can provide the SOA array chip209 on the uplink (capable of handling both polarizations). In someembodiments, the TORminator module 107 can provide both the SOA arraychip 207 on the downlink and the SOA array chip 209 on the uplink(capable of handling both polarizations).

In some embodiments, the TORminator module 107 is edge-connectorpluggable. In some embodiments, the TORminator module 107 is on amezzanine card. In some embodiments, one or more components of theTORminator module 107 are directly socketed on the EOR/MOR switchlinecard 101. In some embodiments, the TeraPHY chip 203 of theTORminator module 107 is co-packaged with the switch chip within therack switch 103, while the laser chip 205 and SOA array chips 207, 209of the TORminator module 107 are either in the TORminator module 107 orsocketed on the EOR/MOR switch linecard 101.

In some embodiments, the TeraPHY chip 203 of the TORminator module 107includes multiple transceiver macros, with each transceiver macro beingof multiple wavelength slices. In some embodiments, the slices of theTeraPHY chip 203 include electrical and optical components (transmit andreceive macro slices). In some embodiments, an electrical link betweenthe TeraPHY chip 203 and the switch chip in the rack switch 103 isretimed. In some embodiments, an electrical link between the TeraPHYchip 203 and the switch chip in the rack switch 103 is not retimed. Insome embodiments, the slices of the TeraPHY chip 203 include onlyoptical components. In some embodiments, modulator slices of the TeraPHYchip 203 modulate a portion of the laser light wavelengths provided bythe laser chip 205 and leave a remainder of the laser light wavelengthsprovided by the laser chip 205 for use by the servers to uplink data.

In some embodiments, a data communication system includes a rack switch103, a TORminator module 107, a downlink optical fiber d1 to dK, anuplink optical fiber u1 to uK, and a SmartDistribuTOR module 111-x. TheTORminator module 107 is electrically connected to the rack switch 103.The TORminator module 107 is configured to convert a number (N) ofdownlink data communication electrical signals received from the rackswitch 103 into corresponding N downlink data communication opticalsignals, where N is greater than one. Each of the N downlink datacommunication optical signals has a different optical wavelength. TheTORminator module 107 is configured to simultaneously direct the Ndownlink data communication optical signals to a first downlink opticalport (half of each of 109-1 to 109-K). The TORminator module 107 isconfigured to generate N different wavelengths of continuous wave laserlight and simultaneously direct the N different wavelengths ofcontinuous wave laser light to the first downlink optical port (half ofeach of 109-1 to 109-K). The TORminator module 107 includes a firstuplink optical port (half of each of 109-1 to 109-K). The TORminatormodule 107 is configured to convert N uplink data communication opticalsignals received through the first uplink optical port (half of each of109-1 to 109-K) into N uplink data communication electrical signals. TheTORminator module 107 is configured to transmit the N uplink datacommunication electrical signals to the rack switch 103.

The downlink optical fiber d1 to dK has a first end optically coupled tothe first downlink optical port (half of each of 109-1 to 109-K) of theTORminator module 107. The uplink optical fiber u1 to uK has a first endoptically coupled to the first uplink optical port (half of each of109-1 to 109-K) of the TORminator module 107. The SmartDistribuTORmodule 111-x has a second downlink optical port (half of 113), a seconduplink optical port (half of 113), N server downlink optical ports S1 dto SNd, and N server uplink optical ports S1 u to SNu. The downlinkoptical fiber d1 to dK has a second end optically coupled to the seconddownlink optical port (half of 113). The uplink optical fiber u1 to uKhas a second end optically coupled to the second uplink optical port(half of 113). The SmartDistribuTOR module 111-x is configured torespectively direct the N downlink data communication optical signalsand the N different wavelengths of continuous wave laser light receivedthrough the second downlink optical port (half of 113) to the N serverdownlink optical ports S1 d to SNd. The SmartDistribuTOR module 111-x isalso configured to simultaneously direct N uplink data communicationoptical signals received through the N server uplink optical ports S1 uto SNu to the second uplink optical port (half of 113).

In the data communication system, each of N servers is opticallyconnected to a respective one of the N server downlink optical ports S1d to SNd of the SmartDistribuTOR module 111-x and to a respective one ofthe N server uplink optical ports S1 u to SNu of the SmartDistribuTORmodule 111-x. Each of the N servers includes a reverb module 601 havingan optical input port 607A and an optical output port 607B. The opticalinput port 607A of the reverb module 601 optically connected to therespective one of the N server downlink optical ports S1 d to SNd of theSmartDistribuTOR module 111-x. The optical output port 607B of thereverb module 601 optically connected to the respective one of the Nserver uplink optical ports S1 u to SNu of the SmartDistribuTOR module111-x. The reverb module 601 configured to convert a respective one ofthe N downlink data communication optical signals 704 received throughthe optical input port 607A into a corresponding downlink datacommunication electrical signal for processing by the corresponding oneof the N servers that includes the reverb module 601. The reverb module601 configured to convert an uplink data communication electrical signalprovided by the corresponding one of the N servers that includes thereverb module into an uplink data communication optical signal 706 fortransmission through the optical output port 607B of the reverb module601.

In some embodiments, the reverb module 601 is configured to modulate arespective one of the N different wavelengths of continuous wave laserlight 702 received through the optical input port 607A to convert theuplink data communication electrical signal provided by thecorresponding one of the N servers into the uplink data communicationoptical signal 706 for transmission through the optical output port 607Bof the reverb module 601.

In some embodiments, the reverb module 601 includes theserializer/deserializer (SerDes) chip 605 configured to deserializeserial downlink data within the corresponding downlink datacommunication electrical signal that is converted from the respectiveone of the N downlink data communication optical signals 704 receivedthrough the optical input port 607A to obtain parallel downlink data forprocessing by the corresponding one of the N servers that includes thereverb module 601. In some embodiments, the SerDes chip 605 of thereverb module 601 is configured to serialize parallel uplink dataprovided by the corresponding one of the N servers that includes thereverb module 601 to generate the uplink data communication electricalsignal prior to modulation of the respective one of the N differentwavelengths of continuous wave laser light 702 received through theoptical input port 607A in order to convert the uplink datacommunication electrical signal into the uplink data communicationoptical signal 706 for transmission through the optical output port 607Bof the reverb module 601.

In some embodiments, the TORminator module 107 includes the SerDes chip201 connected to the rack switch 103. The SerDes chip 201 is configuredto serialize parallel downlink data received from the rack switch 103.The SerDes chip 301 is also configured to deserialize serial uplink datawithin the N uplink data communication electrical signals fortransmission to the rack switch 103. Also, in some embodiments, theTORminator module 107 includes the laser chip 205 configured andconnected to generate the N different wavelengths of continuous wavelaser light. In some embodiments, the TORminator module 107 includes theoptical amplifier (SOA) chip 207 configured and connected to amplify theN downlink data communication optical signals prior to being directed tothe first downlink optical port (half of each of 109-1 to 109-K). Insome embodiments, the TORminator module 107 includes an opticalamplifier (SOA) chip 209 configured and connected to amplify the Nuplink data communication optical signals received through the firstuplink optical port (half of each of 109-1 to 109-K).

In some embodiments, the SmartDistribuTOR module 111-x is configured todirect the N downlink data communication optical signals receivedthrough the second downlink optical port (half of 113) into N separateoptical channels Ch1 to ChN, and the SmartDistribuTOR module 111-x isconfigured to direct the N different wavelengths of continuous wavelaser light received through the second downlink optical port (half of113) into the N separate optical channels Ch1 to ChN, such that each ofthe N separate optical channels Ch1 to ChN includes a different one ofthe N downlink data communication optical signals and a different one ofthe N different wavelengths of continuous wave laser light. TheSmartDistribuTOR module 111-x is also configured to aggregate the Nuplink data communication optical signals onto a single opticalwaveguide 117 for transmission through the second uplink optical port(half of 113). In some embodiments, the number N of separate opticalchannels Ch1 to ChN is 8.

In some embodiments, the TORminator module 107 is configured andconnected to receive a number (M) of downlink data communicationelectrical signals from the rack switch 103, where M is an integer (K)multiple of N, i.e., M=(K)(N). The TORminator module 107 is configuredto convert the M downlink data communication electrical signals intocorresponding M downlink data communication optical signals. The Mdownlink data communication optical signals are distributed into K setsof N downlink data communication optical signals per set. Each of the Ndownlink data communication optical signals in a given one of the K setshas a different optical wavelength. The TORminator module 107 isconfigured to simultaneously direct the N downlink data communicationoptical signals in a given one of the K sets to a respective one of Kdownlink optical ports (half of each of 109-1 to 109-K) of theTORminator module 107. The TORminator module 107 is configured tosimultaneously direct the N different wavelengths of continuous wavelaser light to each of the K downlink optical ports (half of each of109-1 to 109-K) of the TORminator module 107. The TORminator module 107includes K uplink optical ports (half of each of 109-1 to 109-K). TheTORminator module 107 configured to convert N uplink data communicationoptical signals received through each of the K uplink optical ports(half of each of 109-1 to 109-K) into N uplink data communicationelectrical signals to constitute M uplink data communication electricalsignals. The TORminator module 107 configured to transmit the M uplinkdata communication electrical signals to the rack switch 103. In someembodiments, K is 16, N is 8, and M is 128. However, in otherembodiments, K is greater or less than 16, and/or N is greater or lessthan 8, and M equals N multiplied by K.

In some embodiments, each of K downlink optical fibers d1 to dK has afirst end optically coupled to a respective one of the K downlinkoptical ports (half of each of 109-1 to 109-K) of the TORminator module107. And, each of K uplink optical fibers u1 to uK has a first endoptically coupled to a respective one of the K uplink optical ports(half of each of 109-1 to 109-K) of the TORminator module 107. Also,each of the K downlink optical fibers d1 to dK has a second endoptically coupled to a downlink optical port (half of 113) of arespective one of the K SmartDistribuTOR modules 111-1 to 111-K. Also,each of the K uplink optical fibers u1 to uK has a second end opticallycoupled to an uplink optical port (half of 113) of a respective one ofthe K SmartDistribuTOR modules 111-1 to 111-K. Each of the KSmartDistribuTOR modules 111-1 to 111-K has N server downlink opticalports S1 d to SNd and N server uplink optical ports S1 u to SNu. Each ofthe K SmartDistribuTOR modules 111-1 to 111-K is configured torespectively direct the N downlink data communication optical signalsand the N different wavelengths of continuous wave laser light receivedthrough its downlink optical port (half of 113) to its N server downlinkoptical ports S1 d to SNd. Each of the K SmartDistribuTOR modules 111-1to 111-K is configured to simultaneously direct N uplink datacommunication optical signals received through its N server uplinkoptical ports S1 u to SNu to its uplink optical port (half of 113).

Each of the N server downlink optical ports S1 d to SNd of a given oneof the K SmartDistribuTOR modules 111-1 to 111-K is optically connectedto an optical input of a different server in a set of N servers. Each ofthe N server uplink optical ports S1 u to SNu of the given one of the KSmartDistribuTOR modules 111-1 to 111-K is optically connected to anoptical input of a different server in the set of N servers. In someembodiments, the given one of the K SmartDistribuTOR modules 111-1 to111-K and the set of N servers are disposed in a same rack. In someembodiments, the K SmartDistribuTOR modules 111-1 to 111-K arecollectively connected to optical inputs and optical outputs of Mdifferent servers. In some embodiments, the K SmartDistribuTOR modules111-1 to 111-K and the M different servers are distributed across Kracks, with each of the K racks including a different one of the KSmartDistribuTOR modules 111-1 to 111-K and a unique set of N servers ofthe M different servers. Also, the TORminator module 107 is disposed inone of the K racks.

In some embodiments, an optical multiplexer/demultiplexer module isdisclosed. This optical multiplexer/demultiplexer module is referred toherein as the SmartDistribuTOR module 111-x. The SmartDistribuTOR module111-x includes a downlink optical port (half of 113), an uplink opticalport (half of 113), a number (N) of server downlink optical ports S1 dto SNd, N server uplink optical ports S1 u to SNu, an opticaldemultiplexer 119, and an optical multiplexer 121. The opticaldemultiplexer 119 is configured to separate N downlink datacommunication optical signals received through the downlink optical port(half of 113) based on optical wavelength. The optical demultiplexer 119is configured to respectively direct the N downlink data communicationoptical signals to the N server downlink optical ports S1 d to SNd. Theoptical demultiplexer 119 is also configured to separate N differentwavelengths of continuous wave laser light received through the downlinkoptical port (half of 113) based on optical wavelength. The opticaldemultiplexer 119 configured to respectively direct the N differentwavelengths of continuous wave laser light to the N server downlinkoptical ports S1 d to SNd. The optical multiplexer 121 is configured toaggregate N uplink data communication optical signals received throughthe N server uplink optical ports S1 u to SNu onto a single opticalwaveguide 117 optically coupled to the uplink optical port (half of113).

Each of the N server downlink optical ports S1 d to SNd is opticallycoupled to a respective one of N servers, and each of the N serveruplink optical ports S1 u to SNu is optically coupled to a respectiveone of the N servers. In some embodiments, the SmartDistribuTOR module111-x and the N servers are disposed within a same rack. In someembodiments, the N different wavelengths of continuous wave laser lightare generated by the laser chip 205 disposed separate from theSmartDistribuTOR module 111-x. The SmartDistribuTOR module 111-x isconfigured to separate the N downlink data communication optical signalsinto N separate optical channels. The SmartDistribuTOR module 111-x isalso configured to separate the N different wavelengths of continuouswave laser light into the N separate optical channels. In this manner,each of the N separate optical channels includes a different one of theN downlink data communication optical signals and a different one of theN different wavelengths of continuous wave laser light. In someembodiments, the value of N is 8. However, in other embodiments, thevalue of N is either greater than or less than 8.

In some embodiments, the SmartDistribuTOR module 111-x includes adownlink polarization control device 403 configured to split lightreceived through downlink optical port (half of 113) into a firstpolarization of light and a second polarization of light. In someembodiments, the downlink polarization control device 403 includes apolarization splitting optical grating. In some embodiments, thedownlink polarization control device 403 includes a polarizationindependent optical coupler having an optical output coupled to anoptical input of a polarization splitter-rotator. In some embodiments,the downlink polarization control device 403 includes a thermallycontrolled Mach-Zehnder interferometer configured to combine the firstpolarization of light and the second polarization of light onto thesingle optical waveguide 405.

In some embodiments, the optical demultiplexer 119 includes the tunableoptical ring resonator filterbank 407 that includes N optical ringresonator filters 413(1) to 413(N). Each of the N optical ring resonatorfilters 413(1) to 413(N) includes at least one ring resonator 417(1) to417(N) configured to drop one or more wavelengths of the N downlink datacommunication optical signals to a photodetector corresponding to theoptical ring resonator filter 417(1) to 417(N). In some embodiments, thephotodetector is integrated within the optical ring resonator filter413(1) to 413(N). Additional description of photodetector integrationwithin an optical ring resonator is provided in U.S. patent applicationSer. No. 15/687,413, which is incorporated in its entirety herein byreference for all purposes. In some embodiments, the photodetector isconfigured and connected to operate as a sensor for wavelength lockwithin the optical ring resonator filter 413(1) to 413(N). In someembodiments, the optical demultiplexer 119 includes heaters 415(1) to415(N) respectively embedded within the at least one ring resonator417(1) to 417(N). The heaters 415(1) to 415(N) are electricallycontrollable to enable control of respective resonant wavelength of theat least one ring resonator 417(1) to 417(N). In some embodiments, theoptical demultiplexer 119 includes embedded digital control loops 419(1)to 419(N) respectively connected to the heaters 415(1) to 415(N). Agiven embedded digital control loop 419(1) to 419(N) is configured tosense an amount of light that is absorbed within a given ring resonator417(1) to 417(N). In this manner, the embedded digital control loops419(1) to 419(N) are electrically connected to the photodetectors thatare integrated within the optical ring resonator filters 413(1) to413(N), respectively, in order to sense the amount of light that isabsorbed within the ring resonators 417(1) to 417(N).

In some embodiments, the optical multiplexer 121 includes N opticalwaveguides 125(1) to 125(N) respectively optically coupled to the Nserver uplink optical ports S1 u to SNu. The optical multiplexer 121includes N polarization control devices 503(1) to 503(N) opticallycoupled to the N optical waveguides 125(1) to 125(N). Each of the Npolarization control devices 503(1) to 503(N) is configured to splitlight received through the N optical waveguides 125(1) to 125(N) fromthe corresponding N server uplink optical ports S1 u to SNu into a firstpolarization of light and a second polarization of light. In someembodiments, each of the N polarization control devices 503(1) to 503(N)includes a polarization splitting optical grating. In some embodiments,each of the N polarization control devices 503(1) to 503(N) includes apolarization independent optical coupler having an optical outputcoupled to an optical input of a polarization splitter-rotator. In someembodiments, each of the N polarization control devices 503(1) to 503(N)includes a thermally controlled Mach-Zehnder interferometer configuredto combine the first polarization of light and the second polarizationof light onto a single optical waveguide. The optical multiplexer 121includes a tunable optical ring resonator filterbank 511 that includes Noptical ring resonator filters 513(1) to 513(N). Each of the N opticalring resonator filters 513(1) to 513(N) includes at least one ringresonator 517(1) to 517(N) configured to drop one or more wavelengths ofthe N uplink data communication optical signals to a photodetectorcorresponding to the optical ring resonator filter 513(1) to 513(N). Insome embodiments, the photodetector is integrated within the opticalring resonator filter 513(1) to 513(N). In some embodiments, thephotodetector is configured and connected to operate as a sensor forwavelength lock within the optical ring resonator filter 513(1) to513(N).

In some embodiments, the optical multiplexer 121 includes heaters 515(1)to 515(N) respectively embedded within the at least one ring resonator517(1) to 517(N). The heaters 515(1) to 515(N) are electricallycontrollable to enable control of respective resonant wavelength of theat least one ring resonator 517(1) to 517(N). Embedded digital controlloops 519(1) to 519(N) are respectively connected to the heaters 515(1)to 515(N). A given embedded digital control loop 519(1) to 519(N) isconfigured to sense an amount of light that is absorbed within a givenring resonator 517(1) to 517(N). In this manner, the embedded digitalcontrol loops 519(1) to 519(N) are electrically connected to thephotodetectors that are integrated within the optical ring resonatorfilters 513(1) to 513(N), respectively, in order to sense the amount oflight that is absorbed within the ring resonators 517(1) to 517(N). Thetunable optical ring resonator filterbank 511 is configured to aggregateselected ones of the N uplink data communication optical signals ontothe output optical waveguide 512. The output optical waveguide 521 isoptically coupled to the uplink optical port (half of 113) by way of theuplink optical waveguide 117.

In some embodiments, an electro-optical interface module 601 isdisclosed. The electro-optical interface module 601 is also referred toherein as the Reverb module 601. The electro-optical interface module601 includes an optical fiber interface configured to optically coupleto the first optical fiber 607A and the second optical fiber 607B. Theelectro-optical interface module 601 includes the Reverb chip 603(electronic-photonic chip) that includes a first optical coupler and asecond optical coupler. The first optical coupler is configured andconnected to receive light transmitted through the optical fiberinterface from the first optical fiber 607A. The second optical coupleris configured and connected to direct light through the optical fiberinterface to the second optical fiber 607B. In some embodiments, theReverb chip 603 includes the downlink polarization control device 703configured to split light received through the first optical coupler byway of the optical fiber 607A into a first polarization of light and asecond polarization of light. The Reverb chip 603 also includes thedownlink data receiver device 709 configured and connected to receivelight from the downlink polarization control device 703. The downlinkdata receiver device 709 is configured and connected to filter downlinkmodulated light from the light received from the downlink polarizationcontrol device 703, and convert the downlink modulated light into adownlink electrical data signal. The downlink data receiver device 709is configured and connected to direct unmodulated continuous wave lightreceived from the downlink polarization control device 703 to an opticaloutput of the downlink data receiver device 709. In some embodiments,the downlink polarization control device 703 includes a polarizationsplitting optical grating. In some embodiments, the downlinkpolarization control device 703 includes a polarization independentoptical coupler having an optical output coupled to an optical input ofa polarization splitter-rotator. In some embodiments, the downlinkpolarization control device 703 includes a thermally controlledMach-Zehnder interferometer configured to combine the first polarizationof light and the second polarization of light onto a single opticalwaveguide.

The Reverb chip 603 also includes the uplink data modulator device 711configured and connected to receive the unmodulated continuous wavelight from the optical output of the downlink polarization controldevice 709 by way of optical waveguide 705. The uplink data modulatordevice 711 is configured and connected to imprint an uplink electricaldata signal on the unmodulated continuous wave light to generate uplinkmodulated light. The uplink data modulator device 711 is configured andconnected to direct the uplink modulated light to the second opticalcoupler of the Reverb chip 603.

The Reverb chip 603 also includes the electrical input/output block 713configured and connected to receive the downlink electrical data signalfrom the downlink data receiver device 709, and direct the downlinkelectrical data signal to circuitry external to the Reverb chip 603. Theelectrical input/output block 713 is configured and connected to receivethe uplink electrical data signal from circuitry external to the Reverbchip 603 and direct the uplink electrical data signal to the uplink datamodulator device 711.

In some embodiments, the electronic components and photonic componentsof the Reverb chip 603 are integrated monolithically on a same dieformed in a CMOS fabrication process. In some embodiments, the Reverbchip 603 includes electronic circuitry for controlling a polarizationand a resonant wavelength of photonic components within the Reverb chip603. In some embodiments, the Reverb chip 603 includes non-retimedelectronic circuitry including optical receivers and optical modulatordrivers. In some embodiments, the Reverb chip 603 includes retimedelectronic circuitry including a serializer circuit, a deserializercircuit, a clock generator, a phase-lock loop, and a clock-data-recoveryloop.

In some embodiments, the downlink data receiver device 709 includes oneor more resonant ring filters configured to drop one or more wavelengthsof downlink modulated light to one or more photodetectors respectivelycorresponding to the one or more resonant ring filters. In someembodiments, the one or more photodetectors are respectively integratedin the one or more resonant ring filters. In some embodiments, thedownlink data receiver device 709 includes one or more heatersrespectively embedded within the one or more resonant ring filters,where the one or more heaters are electrically controllable to enablecontrol of respective resonant wavelengths of the one or more resonantring filters. In some embodiments, one or more embedded digital controlloops are respectively connected to the one or more heaters, where agiven embedded digital control loop is configured to sense an amount oflight that is absorbed within a given resonant ring filter correspondingto a given heater connected to the given embedded digital control loop.In some embodiments, the one or more embedded digital control loops areimplemented within the Reverb chip 603. In some embodiments, the one ormore embedded digital control loops are implemented within a CMOS chipdifferent from the Reverb chip 603.

In some embodiments, the uplink data modulator device 711 includes oneor more resonant ring modulators respectively tuned to one or morewavelengths of the unmodulated continuous wave light received from theoptical output of the downlink polarization control device 703. In someembodiments, the uplink data receiver device 711 includes one or moreheaters respectively embedded within the one or more resonant ringmodulators, where the one or more heaters are electrically controllableto enable control of respective resonant wavelengths of the one or moreresonant ring modulators. In some embodiments, the one or more embeddeddigital control loops are respectively connected to the one or moreheaters, where a given embedded digital control loop is configured tosense an amount of light that is absorbed within a given resonant ringmodulator corresponding to a given heater connected to the givenembedded digital control loop. In some embodiments, the one or moreembedded digital control loops are implemented within the Reverb chip603. In some embodiments, the one or more embedded digital control loopsare implemented within a CMOS chip different from the Reverb chip 603.

FIG. 10 shows a flowchart of a method for controlling datacommunication, in accordance with some embodiments. The method includesan operation 1001 for receiving a number (N) of downlink datacommunication electrical signals from a rack switch (103) at aTORminator module (107). The value of N is greater than one. The methodalso includes an operation 1003 for operating the TORminator module(107) to convert the N downlink data communication electrical signalsinto corresponding N downlink data communication optical signals. Eachof the N downlink data communication optical signals has a differentoptical wavelength. The method also includes an operation 1005 foroperating the TORminator module (107) to simultaneously direct the Ndownlink data communication optical signals to a first downlink opticalport (half of each of 109-1 to 109-K) of the TORminator module (107).The method also includes an operation 1007 for operating the TORminatormodule (107) to generate N different wavelengths of continuous wavelaser light. In some embodiments, the method includes operating a laserchip (205) within the TORminator module (107) to generate the Ndifferent wavelengths of continuous wave laser light. In someembodiments, the value of N is 8. In some embodiments, the value of N iseither greater than or less than 8. The method also includes anoperation 1009 for operating the TORminator module to simultaneouslydirect the N different wavelengths of continuous wave laser light to thefirst downlink optical port (half of each of 109-1 to 109-K) of theTORminator module (107). The method also includes an operation 1011 foroperating the TORminator module (107) to receive N uplink datacommunication optical signals through a first uplink optical port (halfof each of 109-1 to 109-K) of the TORminator module (107). The methodalso includes an operation 1013 for operating the TORminator module(107) to convert the N uplink data communication optical signals into Nuplink data communication electrical signals. The method also includesan operation 1015 for operating the TORminator module (107) to transmitthe N uplink data communication electrical signals to the rack switch(103).

In some embodiments, the method of FIG. 10 also includes operating aSmartDistribuTOR module (111-x) to simultaneously receive the N downlinkdata communication optical signals and the N different wavelengths ofcontinuous wave laser light from the first downlink optical port of theTORminator module (107) through a single optical waveguide (115). Themethod also includes operating the SmartDistribuTOR module (111-x) torespectively direct the N downlink data communication optical signalsand the N different wavelengths of continuous wave laser light to Nservers, such that each of the N servers receives a different one of theN downlink data communication optical signals and a different one the Ndifferent wavelengths of continuous wave laser light. The method alsoincludes operating the SmartDistribuTOR module (111-x) to receive Nuplink data communication optical signals from the N servers. The methodalso includes operating the SmartDistribuTOR module (111-x) tosimultaneously direct the N uplink data communication optical signalsthrough a single optical waveguide to the TORminator module (107).

In some embodiments, the method of FIG. 10 also includes operating Nreverb modules (601) respectively disposed within the N servers torespectively receive the N downlink data communication optical signalsand the N different wavelengths of continuous wave laser light from theSmartDistribuTOR module (111-x). The method also includes operating eachof the N reverb modules (601) to convert the downlink data communicationoptical signal received from the SmartDistribuTOR module (111-x) into acorresponding data communication electrical signal for processing by theserver in which the reverb module (601) is disposed. The method alsoincludes operating each of the N reverb modules (601) to convert a datacommunication electrical signal provided by the server in which thereverb module (601) is disposed into an uplink data communicationoptical signal. The method also includes operating each of the N reverbmodules (601) to transmit the uplink data communication optical signalto the SmartDistribuTOR module (111-x). Each of the N reverb modules(601) modulates a respective one of the N different wavelengths ofcontinuous wave laser light to convert the data communication electricalsignal provided by the server in which the reverb module (601) isdisposed into the uplink data communication optical signal.

In some embodiments, the method of FIG. 10 includes operating theTORminator module (107) to receive a number (M) of downlink datacommunication electrical signals from the rack switch (103), wherein Mis an integer (K) multiple of N, i.e., M=(K)(N), and where thepreviously mentioned N downlink data communication electrical signalsare included in the M downlink data communication electrical signals. Insome embodiments, K is 16, N is 8, and M is 128. However, in otherembodiments, K is greater or less than 16, and/or N is greater or lessthan 8, and M equals N multiplied by K. The method also includesoperating the TORminator module (107) to convert the M downlink datacommunication electrical signals into corresponding M downlink datacommunication optical signals. The method also includes operating theTORminator module (107) to distribute the M downlink data communicationoptical signals into K sets of N downlink data communication opticalsignals per set. Each of the N downlink data communication opticalsignals in a given one of the K sets has a different optical wavelength.The method also includes operating the TORminator module (107) tosimultaneously direct the N downlink data communication optical signalsin a given one of the K sets to a respective one of K downlink opticalports of the TORminator module (107). The previously mentioned firstdownlink optical port of the TORminator module (107) is a first of the Kdownlink optical ports of the TORminator module (107). The method alsoincludes operating the TORminator module (107) to simultaneously directthe N different wavelengths of continuous wave laser light to each ofthe K downlink optical ports of the TORminator module (107). The methodalso includes operating the TORminator module (107) to receive N uplinkdata communication optical signals through each of K uplink opticalports. The previously mentioned first uplink optical port of theTORminator module (107) is a first of the K uplink optical ports of theTORminator module (107). The method also includes operating theTORminator module (107) to convert the N uplink data communicationoptical signals received through each of the K uplink optical ports intoN uplink data communication electrical signals to constitute M uplinkdata communication electrical signals. The method also includesoperating the TORminator module (107) to transmit the M uplink datacommunication electrical signals to the rack switch (103).

In some embodiments, the method also includes operating each of KSmartDistribuTOR modules (111-1 to 111-K) to receive the N downlink datacommunication optical signals in a corresponding one of the K sets fromthe TORminator module (107). The method also includes operating each ofthe K SmartDistribuTOR modules (111-1 to 111-K) to receive the Ndifferent wavelengths of continuous wave laser light from the TORminatormodule (107). The method also includes operating each of the KSmartDistribuTOR modules (111-1 to 111-K) to separate the N downlinkdata communication optical signals and respectively transmit the Ndownlink data communication optical signals to N servers. The methodalso includes operating each of the K SmartDistribuTOR modules (111-1 to111-K) to respectively transmit the N different wavelengths ofcontinuous wave laser light to the N servers.

The method also includes operating each of the K SmartDistribuTORmodules (111-1 to 111-K) to receive N uplink data communication opticalsignals from the N servers. The method also includes operating each ofthe K SmartDistribuTOR modules (111-1 to 111-K) to aggregate the Nuplink data communication optical signals onto a single opticalwaveguide and transmit the N uplink data communication optical signalsthrough the single optical waveguide to the TORminator module (107),such that the TORminator module (107) collectively receives M uplinkdata communication optical signals from the K SmartDistribuTOR modules(111-1 to 111-K). The method also includes operating the TORminatormodule (107) to convert the M uplink data communication optical signalsinto M uplink data communication electrical signals. The method alsoincludes operating the TORminator module (107) to transmit the M uplinkdata communication electrical signals to the rack switch (103).

FIG. 11 shows a flowchart of a method for operating an opticalmultiplexer/demultiplexer module, in accordance with some embodiments.The optical multiplexer/demultiplexer module of the method of FIG. 11 isthe SmartDistribuTOR module (111-x) disclosed herein. The methodincludes an operation 1101 for receiving a number (N) of downlink datacommunication optical signals through a downlink optical port (half of113). The method also includes an operation 1103 for separating the Ndownlink data communication optical signals into N separate opticalchannels. The method also includes an operation 1105 for receiving Ndifferent wavelengths of continuous wave laser light through thedownlink optical port (half of 113). The method also includes anoperation 1107 for separating the N different wavelengths of continuouswave laser light into the N separate optical channels. The method alsoincludes an operation 1109 for respectively directing the N separateoptical channels to N server downlink optical ports (S1 d to SNd). Themethod also includes an operation 1111 for respectively receiving Nuplink data communication optical signals through the N server uplinkoptical ports (S1 u to SNu). The method also includes an operation 1113for aggregating the N uplink data communication optical signals onto asingle optical waveguide (117) optically coupled to an uplink opticalport (half of 113).

In some embodiments, the method includes transmitting the N downlinkdata communication optical signals through a downlink polarizationcontrol device (403) to split each of the N downlink data communicationoptical signals into a first polarization of light and a secondpolarization of light. In some embodiments, the operation 1103 forseparating the N downlink data communication optical signals into Nseparate optical channels is performed by operating a tunable opticalring resonator filterbank (407) that includes N optical ring resonatorfilters (413(1)-413(N)). Each of the N optical ring resonator filters(413(1)-413(N)) includes at least one ring resonator (417(1)-417(N))operating to drop one or more wavelengths of the N downlink datacommunication optical signals to a photodetector corresponding to theoptical ring resonator filter (413(1)-413(N)).

In some embodiments, operating the tunable optical ring resonatorfilterbank (407) includes operating heaters (415(1)-415(N)) respectivelyembedded within the at least one ring resonator (417(1)-417(N)) tocontrol a respective resonant wavelength of the at least one ringresonator (417(1)-417(N)). In some embodiments, the method includesrespectively transmitting the N uplink data communication opticalsignals through N uplink polarization control devices (503(1)-503(N)) tosplit each of the N uplink data communication optical signals into afirst polarization of light and a second polarization of light. Themethod also includes aggregating the N uplink data communication opticalsignals onto the single optical waveguide (117) includes operating atunable optical ring resonator filterbank (511) that includes N opticalring resonator filters (513(1)-513(N)). Each of the N optical ringresonator filters (513(1)-513(N)) includes at least one ring resonator(517(1)-517(N)) operating to drop one or more wavelengths of the Nuplink data communication optical signals to a photodetectorcorresponding to the optical ring resonator filter (513(1)-513(N)). Insome embodiments, operating the tunable optical ring resonatorfilterbank (511) includes operating heaters (515(1)-515(N)) respectivelyembedded within the at least one ring resonator (517(1)-517(N)) tocontrol a respective resonant wavelength of the at least one ringresonator (517(1)-517(N)).

FIG. 12 shows a flowchart of a method for operating an electro-opticalinterface of a server, in accordance with some embodiments. Theelectro-optical interface of the server is the Reverb module 601disclosed herein. The method includes an operation 1201 for receivingdownlink light through a first optical coupler, where the downlink lightincludes downlink modulated light of a first wavelength and unmodulatedcontinuous wave light of a second wavelength. The method also includesan operation 1203 for filtering the downlink modulated light from thedownlink light. In some embodiments, the method also includes splittingthe downlink light into a first polarization of light and a secondpolarization of light prior to filtering the downlink modulated lightfrom the downlink light in operation 1203. The method also includes anoperation 1205 for converting the downlink modulated light into adownlink electrical data signal. The method also includes an operation1207 for transmitting the downlink electrical data signal to processingcircuitry. The method also includes an operation 1209 for imprinting anuplink electrical data signal on the unmodulated continuous wave lightto generate uplink modulated light. The method also includes anoperation 1211 for transmitting the uplink modulated light through the asecond optical coupler.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications can be practiced within the scope of theinvention description. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the described embodiments.

What is claimed is:
 1. A method for operating an optical module,comprising: receiving a plurality of downlink data communication opticalsignals through a downlink optical port; separating the plurality ofdownlink data communication optical signals into a plurality of separateoptical channels; receiving a plurality of different wavelengths ofcontinuous wave laser light through the downlink optical port, theplurality of different wavelengths of continuous wave laser light beingdifferent than wavelengths respectively corresponding to the pluralityof downlink data communication optical signals; separating the pluralityof different wavelengths of continuous wave laser light into theplurality of separate optical channels; splitting each of the pluralityof downlink data communication optical signals and each of the pluralityof different wavelengths of continuous wave laser light in the pluralityof separate optical channels into two separate polarizations of light;for each of the plurality of downlink data communication optical signalsin the plurality of separate optical channels, rotating one of the twoseparate polarizations of light to another of the two separatepolarizations of light such that each of the plurality of downlink datacommunication optical signals in the plurality of separate opticalchannels is defined by one polarization of light; for each of theplurality of different wavelengths of continuous wave laser light in theplurality of separate optical channels, rotating one of the two separatepolarizations of light to another of the two separate polarizations oflight such that each of the plurality of different wavelengths ofcontinuous wave laser light in the plurality of separate opticalchannels is defined by one polarization of light; conveying each of theplurality of downlink data communication optical signals and each of theplurality of different wavelengths of continuous wave laser light into asame optical waveguide, such that both a non-rotated one of the twoseparate polarizations of light and the rotated one of the two separatepolarizations of light for each of the plurality of downlink datacommunication optical signals and each of the plurality of differentwavelengths of continuous wave laser light are conveyed into the sameoptical waveguide; optically coupling each of the plurality of downlinkdata communication optical signals in the plurality of separate opticalchannels as defined by one polarization of light out of the same opticalwaveguide and into a respective one of a plurality of ring resonatorsthat are positioned along the same optical waveguide; and opticallycoupling each of the plurality of different wavelengths of continuouswave laser light in the plurality of separate optical channels asdefined by one polarization of light out of the same optical waveguideand into a respective one of the plurality of ring resonators that arepositioned along the same optical waveguide, such that each of theplurality of ring resonators has an optical incoupling of both a uniqueone of the plurality of downlink data communication optical signals anda unique one of the plurality of different wavelengths of continuouswave laser light.
 2. The method as recited in claim 1, wherein splittingeach of the plurality of downlink data communication optical signals inthe plurality of separate optical channels includes transmitting theplurality of downlink data communication optical signals through apolarization splitting optical grating.
 3. The method as recited inclaim 1, wherein splitting each of the plurality of downlink datacommunication optical signals in the plurality of separate opticalchannels into two separate polarizations of light includes transmittingthe plurality of downlink data communication optical signals through adownlink polarization control device.
 4. The method as recited in claim3, wherein the downlink polarization control device includes apolarization splitter-rotator.
 5. The method as recited in claim 1,wherein a portion of the same optical waveguide that extends past theplurality of ring resonators is substantially linear-shaped.
 6. Themethod as recited in claim 1, wherein a thermally controlledMach-Zehnder interferometer is used to combine both the non-rotated oneof the two separate polarizations of light and the rotated one of thetwo separate polarizations of light onto the same optical waveguide. 7.The method as recited in claim 1, wherein the same optical waveguide ispositioned within an optical coupling distance of each of the pluralityof ring resonators.
 8. The method as recited in claim 1, furthercomprising: controlling a resonant wavelength of the respective one ofthe plurality of ring resonators to substantially match a wavelength ofthe non-rotated one of the two separate polarizations of light and therotated one of the two separate polarizations of light within the sameoptical waveguide.
 9. The method as recited in claim 8, whereincontrolling the resonant wavelength of the respective one of theplurality of ring resonators is done by controlling a heater positionednext to the respective one of the plurality of ring resonators.
 10. Themethod as recited in claim 1, wherein separating the plurality ofdownlink data communication optical signals into the plurality ofseparate optical channels is performed by operating a tunable opticalring resonator filterbank that includes a plurality of optical ringresonator filters.
 11. The method as recited in claim 10, furthercomprising: operating each one of the plurality of optical ringresonator filters to drop one or more wavelengths of the plurality ofdownlink data communication optical signals to a photodetectorcorresponding to said one of the plurality of optical ring resonatorfilters.
 12. The method as recited in claim 10, further comprising:operating a plurality of heaters respectively embedded within theplurality of optical ring resonator filters to control respectiveresonant wavelengths of the plurality of optical ring resonator filters.13. The method as recited in claim 12, further comprising: operating aplurality of embedded digital control loops to respectively control theplurality of heaters to respectively optimize optical coupling of lightinto the plurality of optical ring resonator filters.
 14. The method asrecited in claim 1, further comprising: receiving a plurality of uplinkdata communication optical signals through a plurality of server uplinkoptical ports; and aggregating the plurality of uplink datacommunication optical signals onto a single optical waveguide opticallycoupled to an uplink optical port.
 15. The method as recited in claim14, further comprising: respectively transmitting the plurality ofuplink data communication optical signals through a plurality of uplinkpolarization control devices to split each of the plurality of uplinkdata communication optical signals into two separate polarizations oflight.
 16. The method as recited in claim 14, wherein aggregating theplurality of uplink data communication optical signals onto the singleoptical waveguide includes operating a tunable optical ring resonatorfilterbank that includes a plurality of optical ring resonator filters,wherein each of the plurality of optical ring resonator filters includesa ring resonator operating to drop one or more wavelengths of theplurality of uplink data communication optical signals to aphotodetector optically connected to the ring resonator.
 17. The methodas recited in claim 16, wherein operating the tunable optical ringresonator filterbank includes operating heaters positioned next to thering resonators of the plurality of optical ring resonator filters tocontrol resonant wavelengths of the ring resonators.
 18. The method asrecited in claim 17, further comprising: operating a plurality ofembedded digital control loops to independently control the heaters tooptimize optical coupling of light into the ring resonators of theplurality of optical ring resonator filters.
 19. The method as recitedin claim 18, wherein each of the plurality of embedded digital controlloops operates to maximize a photocurrent generated by thephotodetector.